/*!
 * FullCalendar v2.2.5
 * Docs & License: http://arshaw.com/fullcalendar/
 * (c) 2013 Adam Shaw
 */

(function (factory) {
    if (typeof define === 'function' && define.amd) {
        define(['jquery', 'moment'], factory);
    } else {
        factory(jQuery, moment);
    }
})(function ($, moment) {

    var defaults = {

        titleRangeSeparator: ' \u2014 ', // emphasized dash
        monthYearFormat: 'MMMM YYYY', // required for en. other languages rely on datepicker computable option

        defaultTimedEventDuration: '02:00:00',
        defaultAllDayEventDuration: {days: 1},
        forceEventDuration: false,
        nextDayThreshold: '09:00:00', // 9am

        // display
        defaultView: 'month',
        aspectRatio: 1.35,
        header: {
            left: 'title',
            center: '',
            right: 'today prev,next'
        },
        weekends: true,
        weekNumbers: false,

        weekNumberTitle: 'W',
        weekNumberCalculation: 'local',

        //editable: false,

        // event ajax
        lazyFetching: true,
        startParam: 'start',
        endParam: 'end',
        timezoneParam: 'timezone',

        timezone: false,

        //allDayDefault: undefined,

        // locale
        isRTL: false,
        defaultButtonText: {
            prev: "prev",
            next: "next",
            prevYear: "prev year",
            nextYear: "next year",
            today: 'today',
            month: 'month',
            week: 'week',
            day: 'day'
        },

        buttonIcons: {
            prev: 'left-single-arrow',
            next: 'right-single-arrow',
            prevYear: 'left-double-arrow',
            nextYear: 'right-double-arrow'
        },

        // jquery-ui theming
        theme: false,
        themeButtonIcons: {
            prev: 'circle-triangle-w',
            next: 'circle-triangle-e',
            prevYear: 'seek-prev',
            nextYear: 'seek-next'
        },

        dragOpacity: .75,
        dragRevertDuration: 500,
        dragScroll: true,

        //selectable: false,
        unselectAuto: true,

        dropAccept: '*',

        eventLimit: false,
        eventLimitText: 'more',
        eventLimitClick: 'popover',
        dayPopoverFormat: 'LL',

        handleWindowResize: true,
        windowResizeDelay: 200 // milliseconds before an updateSize happens

    };


    var englishDefaults = {
        dayPopoverFormat: 'dddd, MMMM D'
    };


// right-to-left defaults
    var rtlDefaults = {
        header: {
            left: 'next,prev today',
            center: '',
            right: 'title'
        },
        buttonIcons: {
            prev: 'right-single-arrow',
            next: 'left-single-arrow',
            prevYear: 'right-double-arrow',
            nextYear: 'left-double-arrow'
        },
        themeButtonIcons: {
            prev: 'circle-triangle-e',
            next: 'circle-triangle-w',
            nextYear: 'seek-prev',
            prevYear: 'seek-next'
        }
    };

    var fc = $.fullCalendar = {version: "2.2.5"};
    var fcViews = fc.views = {};


    $.fn.fullCalendar = function (options) {
        var args = Array.prototype.slice.call(arguments, 1); // for a possible method call
        var res = this; // what this function will return (this jQuery object by default)

        this.each(function (i, _element) { // loop each DOM element involved
            var element = $(_element);
            var calendar = element.data('fullCalendar'); // get the existing calendar object (if any)
            var singleRes; // the returned value of this single method call

            // a method call
            if (typeof options === 'string') {
                if (calendar && $.isFunction(calendar[options])) {
                    singleRes = calendar[options].apply(calendar, args);
                    if (!i) {
                        res = singleRes; // record the first method call result
                    }
                    if (options === 'destroy') { // for the destroy method, must remove Calendar object data
                        element.removeData('fullCalendar');
                    }
                }
            }
            // a new calendar initialization
            else if (!calendar) { // don't initialize twice
                calendar = new Calendar(element, options);
                element.data('fullCalendar', calendar);
                calendar.render();
            }
        });

        return res;
    };


// function for adding/overriding defaults
    function setDefaults(d) {
        mergeOptions(defaults, d);
    }


// Recursively combines option hash-objects.
// Better than `$.extend(true, ...)` because arrays are not traversed/copied.
//
// called like:
//     mergeOptions(target, obj1, obj2, ...)
//
    function mergeOptions(target) {

        function mergeIntoTarget(name, value) {
            if ($.isPlainObject(value) && $.isPlainObject(target[name]) && !isForcedAtomicOption(name)) {
                // merge into a new object to avoid destruction
                target[name] = mergeOptions({}, target[name], value); // combine. `value` object takes precedence
            } else if (value !== undefined) { // only use values that are set and not undefined
                target[name] = value;
            }
        }

        for (var i = 1; i < arguments.length; i++) {
            $.each(arguments[i], mergeIntoTarget);
        }

        return target;
    }


// overcome sucky view-option-hash and option-merging behavior messing with options it shouldn't
    function isForcedAtomicOption(name) {
        // Any option that ends in "Time" or "Duration" is probably a Duration,
        // and these will commonly be specified as plain objects, which we don't want to mess up.
        return /(Time|Duration)$/.test(name);
    }
// FIX: find a different solution for view-option-hashes and have a whitelist
// for options that can be recursively merged.

    var langOptionHash = fc.langs = {}; // initialize and expose


// TODO: document the structure and ordering of a FullCalendar lang file
// TODO: rename everything "lang" to "locale", like what the moment project did


// Initialize jQuery UI datepicker translations while using some of the translations
// Will set this as the default language for datepicker.
    fc.datepickerLang = function (langCode, dpLangCode, dpOptions) {

        // get the FullCalendar internal option hash for this language. create if necessary
        var fcOptions = langOptionHash[langCode] || (langOptionHash[langCode] = {});

        // transfer some simple options from datepicker to fc
        fcOptions.isRTL = dpOptions.isRTL;
        fcOptions.weekNumberTitle = dpOptions.weekHeader;

        // compute some more complex options from datepicker
        $.each(dpComputableOptions, function (name, func) {
            fcOptions[name] = func(dpOptions);
        });

        // is jQuery UI Datepicker is on the page?
        if ($.datepicker) {

            // Register the language data.
            // FullCalendar and MomentJS use language codes like "pt-br" but Datepicker
            // does it like "pt-BR" or if it doesn't have the language, maybe just "pt".
            // Make an alias so the language can be referenced either way.
            $.datepicker.regional[dpLangCode] =
                    $.datepicker.regional[langCode] = // alias
                    dpOptions;

            // Alias 'en' to the default language data. Do this every time.
            $.datepicker.regional.en = $.datepicker.regional[''];

            // Set as Datepicker's global defaults.
            $.datepicker.setDefaults(dpOptions);
        }
    };


// Sets FullCalendar-specific translations. Will set the language as the global default.
    fc.lang = function (langCode, newFcOptions) {
        var fcOptions;
        var momOptions;

        // get the FullCalendar internal option hash for this language. create if necessary
        fcOptions = langOptionHash[langCode] || (langOptionHash[langCode] = {});

        // provided new options for this language? merge them in
        if (newFcOptions) {
            mergeOptions(fcOptions, newFcOptions);
        }

        // compute language options that weren't defined.
        // always do this. newFcOptions can be undefined when initializing from i18n file,
        // so no way to tell if this is an initialization or a default-setting.
        momOptions = getMomentLocaleData(langCode); // will fall back to en
        $.each(momComputableOptions, function (name, func) {
            if (fcOptions[name] === undefined) {
                fcOptions[name] = func(momOptions, fcOptions);
            }
        });

        // set it as the default language for FullCalendar
        defaults.lang = langCode;
    };


// NOTE: can't guarantee any of these computations will run because not every language has datepicker
// configs, so make sure there are English fallbacks for these in the defaults file.
    var dpComputableOptions = {

        defaultButtonText: function (dpOptions) {
            return {
                // the translations sometimes wrongly contain HTML entities
                prev: stripHtmlEntities(dpOptions.prevText),
                next: stripHtmlEntities(dpOptions.nextText),
                today: stripHtmlEntities(dpOptions.currentText)
            };
        },

        // Produces format strings like "MMMM YYYY" -> "September 2014"
        monthYearFormat: function (dpOptions) {
            return dpOptions.showMonthAfterYear ?
                    'YYYY[' + dpOptions.yearSuffix + '] MMMM' :
                    'MMMM YYYY[' + dpOptions.yearSuffix + ']';
        }

    };

    var momComputableOptions = {

        // Produces format strings like "ddd MM/DD" -> "Fri 12/10"
        dayOfMonthFormat: function (momOptions, fcOptions) {
            var format = momOptions.longDateFormat('l'); // for the format like "M/D/YYYY"

            // strip the year off the edge, as well as other misc non-whitespace chars
            format = format.replace(/^Y+[^\w\s]*|[^\w\s]*Y+$/g, '');

            if (fcOptions.isRTL) {
                format += ' ddd'; // for RTL, add day-of-week to end
            } else {
                format = 'ddd ' + format; // for LTR, add day-of-week to beginning
            }
            return format;
        },

        // Produces format strings like "H(:mm)a" -> "6pm" or "6:30pm"
        smallTimeFormat: function (momOptions) {
            return momOptions.longDateFormat('LT')
                    .replace(':mm', '(:mm)')
                    .replace(/(\Wmm)$/, '($1)') // like above, but for foreign langs
                    .replace(/\s*a$/i, 'a'); // convert AM/PM/am/pm to lowercase. remove any spaces beforehand
        },

        // Produces format strings like "H(:mm)t" -> "6p" or "6:30p"
        extraSmallTimeFormat: function (momOptions) {
            return momOptions.longDateFormat('LT')
                    .replace(':mm', '(:mm)')
                    .replace(/(\Wmm)$/, '($1)') // like above, but for foreign langs
                    .replace(/\s*a$/i, 't'); // convert to AM/PM/am/pm to lowercase one-letter. remove any spaces beforehand
        },

        // Produces format strings like "H:mm" -> "6:30" (with no AM/PM)
        noMeridiemTimeFormat: function (momOptions) {
            return momOptions.longDateFormat('LT')
                    .replace(/\s*a$/i, ''); // remove trailing AM/PM
        }

    };


// Returns moment's internal locale data. If doesn't exist, returns English.
// Works with moment-pre-2.8
    function getMomentLocaleData(langCode) {
        var func = moment.localeData || moment.langData;
        return func.call(moment, langCode) ||
                func.call(moment, 'en'); // the newer localData could return null, so fall back to en
    }


// Initialize English by forcing computation of moment-derived options.
// Also, sets it as the default.
    fc.lang('en', englishDefaults);

// exports
    fc.intersectionToSeg = intersectionToSeg;
    fc.applyAll = applyAll;
    fc.debounce = debounce;


    /* FullCalendar-specific DOM Utilities
     ----------------------------------------------------------------------------------------------------------------------*/


// Given the scrollbar widths of some other container, create borders/margins on rowEls in order to match the left
// and right space that was offset by the scrollbars. A 1-pixel border first, then margin beyond that.
    function compensateScroll(rowEls, scrollbarWidths) {
        if (scrollbarWidths.left) {
            rowEls.css({
                'border-left-width': 1,
                'margin-left': scrollbarWidths.left - 1
            });
        }
        if (scrollbarWidths.right) {
            rowEls.css({
                'border-right-width': 1,
                'margin-right': scrollbarWidths.right - 1
            });
        }
    }


// Undoes compensateScroll and restores all borders/margins
    function uncompensateScroll(rowEls) {
        rowEls.css({
            'margin-left': '',
            'margin-right': '',
            'border-left-width': '',
            'border-right-width': ''
        });
    }


// Make the mouse cursor express that an event is not allowed in the current area
    function disableCursor() {
        $('body').addClass('fc-not-allowed');
    }


// Returns the mouse cursor to its original look
    function enableCursor() {
        $('body').removeClass('fc-not-allowed');
    }


// Given a total available height to fill, have `els` (essentially child rows) expand to accomodate.
// By default, all elements that are shorter than the recommended height are expanded uniformly, not considering
// any other els that are already too tall. if `shouldRedistribute` is on, it considers these tall rows and 
// reduces the available height.
    function distributeHeight(els, availableHeight, shouldRedistribute) {

        // *FLOORING NOTE*: we floor in certain places because zoom can give inaccurate floating-point dimensions,
        // and it is better to be shorter than taller, to avoid creating unnecessary scrollbars.

        var minOffset1 = Math.floor(availableHeight / els.length); // for non-last element
        var minOffset2 = Math.floor(availableHeight - minOffset1 * (els.length - 1)); // for last element *FLOORING NOTE*
        var flexEls = []; // elements that are allowed to expand. array of DOM nodes
        var flexOffsets = []; // amount of vertical space it takes up
        var flexHeights = []; // actual css height
        var usedHeight = 0;

        undistributeHeight(els); // give all elements their natural height

        // find elements that are below the recommended height (expandable).
        // important to query for heights in a single first pass (to avoid reflow oscillation).
        els.each(function (i, el) {
            var minOffset = i === els.length - 1 ? minOffset2 : minOffset1;
            var naturalOffset = $(el).outerHeight(true);

            if (naturalOffset < minOffset) {
                flexEls.push(el);
                flexOffsets.push(naturalOffset);
                flexHeights.push($(el).height());
            } else {
                // this element stretches past recommended height (non-expandable). mark the space as occupied.
                usedHeight += naturalOffset;
            }
        });

        // readjust the recommended height to only consider the height available to non-maxed-out rows.
        if (shouldRedistribute) {
            availableHeight -= usedHeight;
            minOffset1 = Math.floor(availableHeight / flexEls.length);
            minOffset2 = Math.floor(availableHeight - minOffset1 * (flexEls.length - 1)); // *FLOORING NOTE*
        }

        // assign heights to all expandable elements
        $(flexEls).each(function (i, el) {
            var minOffset = i === flexEls.length - 1 ? minOffset2 : minOffset1;
            var naturalOffset = flexOffsets[i];
            var naturalHeight = flexHeights[i];
            var newHeight = minOffset - (naturalOffset - naturalHeight); // subtract the margin/padding

            if (naturalOffset < minOffset) { // we check this again because redistribution might have changed things
                $(el).height(newHeight);
            }
        });
    }


// Undoes distrubuteHeight, restoring all els to their natural height
    function undistributeHeight(els) {
        els.height('');
    }


// Given `els`, a jQuery set of <td> cells, find the cell with the largest natural width and set the widths of all the
// cells to be that width.
// PREREQUISITE: if you want a cell to take up width, it needs to have a single inner element w/ display:inline
    function matchCellWidths(els) {
        var maxInnerWidth = 0;

        els.find('> *').each(function (i, innerEl) {
            var innerWidth = $(innerEl).outerWidth();
            if (innerWidth > maxInnerWidth) {
                maxInnerWidth = innerWidth;
            }
        });

        maxInnerWidth++; // sometimes not accurate of width the text needs to stay on one line. insurance

        els.width(maxInnerWidth);

        return maxInnerWidth;
    }


// Turns a container element into a scroller if its contents is taller than the allotted height.
// Returns true if the element is now a scroller, false otherwise.
// NOTE: this method is best because it takes weird zooming dimensions into account
    function setPotentialScroller(containerEl, height) {
        containerEl.height(height).addClass('fc-scroller');

        // are scrollbars needed?
        if (containerEl[0].scrollHeight - 1 > containerEl[0].clientHeight) { // !!! -1 because IE is often off-by-one :(
            return true;
        }

        unsetScroller(containerEl); // undo
        return false;
    }


// Takes an element that might have been a scroller, and turns it back into a normal element.
    function unsetScroller(containerEl) {
        containerEl.height('').removeClass('fc-scroller');
    }


    /* General DOM Utilities
     ----------------------------------------------------------------------------------------------------------------------*/


// borrowed from https://github.com/jquery/jquery-ui/blob/1.11.0/ui/core.js#L51
    function getScrollParent(el) {
        var position = el.css('position'),
                scrollParent = el.parents().filter(function () {
            var parent = $(this);
            return (/(auto|scroll)/).test(
                    parent.css('overflow') + parent.css('overflow-y') + parent.css('overflow-x')
                    );
        }).eq(0);

        return position === 'fixed' || !scrollParent.length ? $(el[0].ownerDocument || document) : scrollParent;
    }


// Given a container element, return an object with the pixel values of the left/right scrollbars.
// Left scrollbars might occur on RTL browsers (IE maybe?) but I have not tested.
// PREREQUISITE: container element must have a single child with display:block
    function getScrollbarWidths(container) {
        var containerLeft = container.offset().left;
        var containerRight = containerLeft + container.width();
        var inner = container.children();
        var innerLeft = inner.offset().left;
        var innerRight = innerLeft + inner.outerWidth();

        return {
            left: innerLeft - containerLeft,
            right: containerRight - innerRight
        };
    }


// Returns a boolean whether this was a left mouse click and no ctrl key (which means right click on Mac)
    function isPrimaryMouseButton(ev) {
        return ev.which == 1 && !ev.ctrlKey;
    }


    /* FullCalendar-specific Misc Utilities
     ----------------------------------------------------------------------------------------------------------------------*/


// Creates a basic segment with the intersection of the two ranges. Returns undefined if no intersection.
// Expects all dates to be normalized to the same timezone beforehand.
// TODO: move to date section?
    function intersectionToSeg(subjectRange, constraintRange) {
        var subjectStart = subjectRange.start;
        var subjectEnd = subjectRange.end;
        var constraintStart = constraintRange.start;
        var constraintEnd = constraintRange.end;
        var segStart, segEnd;
        var isStart, isEnd;

        if (subjectEnd > constraintStart && subjectStart < constraintEnd) { // in bounds at all?

            if (subjectStart >= constraintStart) {
                segStart = subjectStart.clone();
                isStart = true;
            } else {
                segStart = constraintStart.clone();
                isStart = false;
            }

            if (subjectEnd <= constraintEnd) {
                segEnd = subjectEnd.clone();
                isEnd = true;
            } else {
                segEnd = constraintEnd.clone();
                isEnd = false;
            }

            return {
                start: segStart,
                end: segEnd,
                isStart: isStart,
                isEnd: isEnd
            };
        }
    }


    function smartProperty(obj, name) { // get a camel-cased/namespaced property of an object
        obj = obj || {};
        if (obj[name] !== undefined) {
            return obj[name];
        }
        var parts = name.split(/(?=[A-Z])/),
                i = parts.length - 1, res;
        for (; i >= 0; i--) {
            res = obj[parts[i].toLowerCase()];
            if (res !== undefined) {
                return res;
            }
        }
        return obj['default'];
    }


    /* Date Utilities
     ----------------------------------------------------------------------------------------------------------------------*/

    var dayIDs = ['sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat'];
    var intervalUnits = ['year', 'month', 'week', 'day', 'hour', 'minute', 'second', 'millisecond'];


// Diffs the two moments into a Duration where full-days are recorded first, then the remaining time.
// Moments will have their timezones normalized.
    function diffDayTime(a, b) {
        return moment.duration({
            days: a.clone().stripTime().diff(b.clone().stripTime(), 'days'),
            ms: a.time() - b.time() // time-of-day from day start. disregards timezone
        });
    }


// Diffs the two moments via their start-of-day (regardless of timezone). Produces whole-day durations.
    function diffDay(a, b) {
        return moment.duration({
            days: a.clone().stripTime().diff(b.clone().stripTime(), 'days')
        });
    }


// Computes the larges whole-unit period of time, as a duration object.
// For example, 48 hours will be {days:2} whereas 49 hours will be {hours:49}.
// Accepts start/end, a range object, or an original duration object.
    /* (never used)
     function computeIntervalDuration(start, end) {
     var durationInput = {};
     var i, unit;
     var val;
     
     for (i = 0; i < intervalUnits.length; i++) {
     unit = intervalUnits[i];
     val = computeIntervalAs(unit, start, end);
     if (val) {
     break;
     }
     }
     
     durationInput[unit] = val;
     return moment.duration(durationInput);
     }
     */


// Computes the unit name of the largest whole-unit period of time.
// For example, 48 hours will be "days" wherewas 49 hours will be "hours".
// Accepts start/end, a range object, or an original duration object.
    function computeIntervalUnit(start, end) {
        var i, unit;

        for (i = 0; i < intervalUnits.length; i++) {
            unit = intervalUnits[i];
            if (computeIntervalAs(unit, start, end)) {
                break;
            }
        }

        return unit; // will be "milliseconds" if nothing else matches
    }


// Computes the number of units the interval is cleanly comprised of.
// If the given unit does not cleanly divide the interval a whole number of times, `false` is returned.
// Accepts start/end, a range object, or an original duration object.
    function computeIntervalAs(unit, start, end) {
        var val;

        if (end != null) { // given start, end
            val = end.diff(start, unit, true);
        } else if (moment.isDuration(start)) { // given duration
            val = start.as(unit);
        } else { // given { start, end } range object
            val = start.end.diff(start.start, unit, true);
        }

        if (val >= 1 && isInt(val)) {
            return val;
        }

        return false;
    }


    function isNativeDate(input) {
        return  Object.prototype.toString.call(input) === '[object Date]' || input instanceof Date;
    }


// Returns a boolean about whether the given input is a time string, like "06:40:00" or "06:00"
    function isTimeString(str) {
        return /^\d+\:\d+(?:\:\d+\.?(?:\d{3})?)?$/.test(str);
    }


    /* General Utilities
     ----------------------------------------------------------------------------------------------------------------------*/

    var hasOwnPropMethod = {}.hasOwnProperty;


// Create an object that has the given prototype. Just like Object.create
    function createObject(proto) {
        var f = function () {};
        f.prototype = proto;
        return new f();
    }


    function copyOwnProps(src, dest) {
        for (var name in src) {
            if (hasOwnProp(src, name)) {
                dest[name] = src[name];
            }
        }
    }


    function hasOwnProp(obj, name) {
        return hasOwnPropMethod.call(obj, name);
    }


// Is the given value a non-object non-function value?
    function isAtomic(val) {
        return /undefined|null|boolean|number|string/.test($.type(val));
    }


    function applyAll(functions, thisObj, args) {
        if ($.isFunction(functions)) {
            functions = [functions];
        }
        if (functions) {
            var i;
            var ret;
            for (i = 0; i < functions.length; i++) {
                ret = functions[i].apply(thisObj, args) || ret;
            }
            return ret;
        }
    }


    function firstDefined() {
        for (var i = 0; i < arguments.length; i++) {
            if (arguments[i] !== undefined) {
                return arguments[i];
            }
        }
    }


    function htmlEscape(s) {
        return (s + '').replace(/&/g, '&amp;')
                .replace(/</g, '&lt;')
                .replace(/>/g, '&gt;')
                .replace(/'/g, '&#039;')
                .replace(/"/g, '&quot;')
                .replace(/\n/g, '<br />');
    }


    function stripHtmlEntities(text) {
        return text.replace(/&.*?;/g, '');
    }


    function capitaliseFirstLetter(str) {
        return str.charAt(0).toUpperCase() + str.slice(1);
    }


    function compareNumbers(a, b) { // for .sort()
        return a - b;
    }


    function isInt(n) {
        return n % 1 === 0;
    }


// Returns a function, that, as long as it continues to be invoked, will not
// be triggered. The function will be called after it stops being called for
// N milliseconds.
// https://github.com/jashkenas/underscore/blob/1.6.0/underscore.js#L714
    function debounce(func, wait) {
        var timeoutId;
        var args;
        var context;
        var timestamp; // of most recent call
        var later = function () {
            var last = +new Date() - timestamp;
            if (last < wait && last > 0) {
                timeoutId = setTimeout(later, wait - last);
            } else {
                timeoutId = null;
                func.apply(context, args);
                if (!timeoutId) {
                    context = args = null;
                }
            }
        };

        return function () {
            context = this;
            args = arguments;
            timestamp = +new Date();
            if (!timeoutId) {
                timeoutId = setTimeout(later, wait);
            }
        };
    }

    var ambigDateOfMonthRegex = /^\s*\d{4}-\d\d$/;
    var ambigTimeOrZoneRegex =
            /^\s*\d{4}-(?:(\d\d-\d\d)|(W\d\d$)|(W\d\d-\d)|(\d\d\d))((T| )(\d\d(:\d\d(:\d\d(\.\d+)?)?)?)?)?$/;
    var newMomentProto = moment.fn; // where we will attach our new methods
    var oldMomentProto = $.extend({}, newMomentProto); // copy of original moment methods
    var allowValueOptimization;
    var setUTCValues; // function defined below
    var setLocalValues; // function defined below


// Creating
// -------------------------------------------------------------------------------------------------

// Creates a new moment, similar to the vanilla moment(...) constructor, but with
// extra features (ambiguous time, enhanced formatting). When given an existing moment,
// it will function as a clone (and retain the zone of the moment). Anything else will
// result in a moment in the local zone.
    fc.moment = function () {
        return makeMoment(arguments);
    };

// Sames as fc.moment, but forces the resulting moment to be in the UTC timezone.
    fc.moment.utc = function () {
        var mom = makeMoment(arguments, true);

        // Force it into UTC because makeMoment doesn't guarantee it
        // (if given a pre-existing moment for example)
        if (mom.hasTime()) { // don't give ambiguously-timed moments a UTC zone
            mom.utc();
        }

        return mom;
    };

// Same as fc.moment, but when given an ISO8601 string, the timezone offset is preserved.
// ISO8601 strings with no timezone offset will become ambiguously zoned.
    fc.moment.parseZone = function () {
        return makeMoment(arguments, true, true);
    };

// Builds an enhanced moment from args. When given an existing moment, it clones. When given a
// native Date, or called with no arguments (the current time), the resulting moment will be local.
// Anything else needs to be "parsed" (a string or an array), and will be affected by:
//    parseAsUTC - if there is no zone information, should we parse the input in UTC?
//    parseZone - if there is zone information, should we force the zone of the moment?
    function makeMoment(args, parseAsUTC, parseZone) {
        var input = args[0];
        var isSingleString = args.length == 1 && typeof input === 'string';
        var isAmbigTime;
        var isAmbigZone;
        var ambigMatch;
        var mom;

        if (moment.isMoment(input)) {
            mom = moment.apply(null, args); // clone it
            transferAmbigs(input, mom); // the ambig flags weren't transfered with the clone
        } else if (isNativeDate(input) || input === undefined) {
            mom = moment.apply(null, args); // will be local
        } else { // "parsing" is required
            isAmbigTime = false;
            isAmbigZone = false;

            if (isSingleString) {
                if (ambigDateOfMonthRegex.test(input)) {
                    // accept strings like '2014-05', but convert to the first of the month
                    input += '-01';
                    args = [input]; // for when we pass it on to moment's constructor
                    isAmbigTime = true;
                    isAmbigZone = true;
                } else if ((ambigMatch = ambigTimeOrZoneRegex.exec(input))) {
                    isAmbigTime = !ambigMatch[5]; // no time part?
                    isAmbigZone = true;
                }
            } else if ($.isArray(input)) {
                // arrays have no timezone information, so assume ambiguous zone
                isAmbigZone = true;
            }
            // otherwise, probably a string with a format

            if (parseAsUTC || isAmbigTime) {
                mom = moment.utc.apply(moment, args);
            } else {
                mom = moment.apply(null, args);
            }

            if (isAmbigTime) {
                mom._ambigTime = true;
                mom._ambigZone = true; // ambiguous time always means ambiguous zone
            } else if (parseZone) { // let's record the inputted zone somehow
                if (isAmbigZone) {
                    mom._ambigZone = true;
                } else if (isSingleString) {
                    mom.zone(input); // if not a valid zone, will assign UTC
                }
            }
        }

        mom._fullCalendar = true; // flag for extended functionality

        return mom;
    }


// A clone method that works with the flags related to our enhanced functionality.
// In the future, use moment.momentProperties
    newMomentProto.clone = function () {
        var mom = oldMomentProto.clone.apply(this, arguments);

        // these flags weren't transfered with the clone
        transferAmbigs(this, mom);
        if (this._fullCalendar) {
            mom._fullCalendar = true;
        }

        return mom;
    };


// Time-of-day
// -------------------------------------------------------------------------------------------------

// GETTER
// Returns a Duration with the hours/minutes/seconds/ms values of the moment.
// If the moment has an ambiguous time, a duration of 00:00 will be returned.
//
// SETTER
// You can supply a Duration, a Moment, or a Duration-like argument.
// When setting the time, and the moment has an ambiguous time, it then becomes unambiguous.
    newMomentProto.time = function (time) {

        // Fallback to the original method (if there is one) if this moment wasn't created via FullCalendar.
        // `time` is a generic enough method name where this precaution is necessary to avoid collisions w/ other plugins.
        if (!this._fullCalendar) {
            return oldMomentProto.time.apply(this, arguments);
        }

        if (time == null) { // getter
            return moment.duration({
                hours: this.hours(),
                minutes: this.minutes(),
                seconds: this.seconds(),
                milliseconds: this.milliseconds()
            });
        } else { // setter

            this._ambigTime = false; // mark that the moment now has a time

            if (!moment.isDuration(time) && !moment.isMoment(time)) {
                time = moment.duration(time);
            }

            // The day value should cause overflow (so 24 hours becomes 00:00:00 of next day).
            // Only for Duration times, not Moment times.
            var dayHours = 0;
            if (moment.isDuration(time)) {
                dayHours = Math.floor(time.asDays()) * 24;
            }

            // We need to set the individual fields.
            // Can't use startOf('day') then add duration. In case of DST at start of day.
            return this.hours(dayHours + time.hours())
                    .minutes(time.minutes())
                    .seconds(time.seconds())
                    .milliseconds(time.milliseconds());
        }
    };

// Converts the moment to UTC, stripping out its time-of-day and timezone offset,
// but preserving its YMD. A moment with a stripped time will display no time
// nor timezone offset when .format() is called.
    newMomentProto.stripTime = function () {
        var a;

        if (!this._ambigTime) {

            // get the values before any conversion happens
            a = this.toArray(); // array of y/m/d/h/m/s/ms

            this.utc(); // set the internal UTC flag (will clear the ambig flags)
            setUTCValues(this, a.slice(0, 3)); // set the year/month/date. time will be zero

            // Mark the time as ambiguous. This needs to happen after the .utc() call, which calls .zone(),
            // which clears all ambig flags. Same with setUTCValues with moment-timezone.
            this._ambigTime = true;
            this._ambigZone = true; // if ambiguous time, also ambiguous timezone offset
        }

        return this; // for chaining
    };

// Returns if the moment has a non-ambiguous time (boolean)
    newMomentProto.hasTime = function () {
        return !this._ambigTime;
    };


// Timezone
// -------------------------------------------------------------------------------------------------

// Converts the moment to UTC, stripping out its timezone offset, but preserving its
// YMD and time-of-day. A moment with a stripped timezone offset will display no
// timezone offset when .format() is called.
    newMomentProto.stripZone = function () {
        var a, wasAmbigTime;

        if (!this._ambigZone) {

            // get the values before any conversion happens
            a = this.toArray(); // array of y/m/d/h/m/s/ms
            wasAmbigTime = this._ambigTime;

            this.utc(); // set the internal UTC flag (will clear the ambig flags)
            setUTCValues(this, a); // will set the year/month/date/hours/minutes/seconds/ms

            if (wasAmbigTime) {
                // the above call to .utc()/.zone() unfortunately clears the ambig flags, so reassign
                this._ambigTime = true;
            }

            // Mark the zone as ambiguous. This needs to happen after the .utc() call, which calls .zone(),
            // which clears all ambig flags. Same with setUTCValues with moment-timezone.
            this._ambigZone = true;
        }

        return this; // for chaining
    };

// Returns of the moment has a non-ambiguous timezone offset (boolean)
    newMomentProto.hasZone = function () {
        return !this._ambigZone;
    };

// this method implicitly marks a zone (will get called upon .utc() and .local())
    newMomentProto.zone = function (tzo) {

        if (tzo != null) { // setter
            // these assignments needs to happen before the original zone method is called.
            // I forget why, something to do with a browser crash.
            this._ambigTime = false;
            this._ambigZone = false;
        }

        return oldMomentProto.zone.apply(this, arguments);
    };

// this method implicitly marks a zone
    newMomentProto.local = function () {
        var a = this.toArray(); // year,month,date,hours,minutes,seconds,ms as an array
        var wasAmbigZone = this._ambigZone;

        oldMomentProto.local.apply(this, arguments); // will clear ambig flags

        if (wasAmbigZone) {
            // If the moment was ambiguously zoned, the date fields were stored as UTC.
            // We want to preserve these, but in local time.
            setLocalValues(this, a);
        }

        return this; // for chaining
    };


// Formatting
// -------------------------------------------------------------------------------------------------

    newMomentProto.format = function () {
        if (this._fullCalendar && arguments[0]) { // an enhanced moment? and a format string provided?
            return formatDate(this, arguments[0]); // our extended formatting
        }
        if (this._ambigTime) {
            return oldMomentFormat(this, 'YYYY-MM-DD');
        }
        if (this._ambigZone) {
            return oldMomentFormat(this, 'YYYY-MM-DD[T]HH:mm:ss');
        }
        return oldMomentProto.format.apply(this, arguments);
    };

    newMomentProto.toISOString = function () {
        if (this._ambigTime) {
            return oldMomentFormat(this, 'YYYY-MM-DD');
        }
        if (this._ambigZone) {
            return oldMomentFormat(this, 'YYYY-MM-DD[T]HH:mm:ss');
        }
        return oldMomentProto.toISOString.apply(this, arguments);
    };


// Querying
// -------------------------------------------------------------------------------------------------

// Is the moment within the specified range? `end` is exclusive.
// FYI, this method is not a standard Moment method, so always do our enhanced logic.
    newMomentProto.isWithin = function (start, end) {
        var a = commonlyAmbiguate([this, start, end]);
        return a[0] >= a[1] && a[0] < a[2];
    };

// When isSame is called with units, timezone ambiguity is normalized before the comparison happens.
// If no units specified, the two moments must be identically the same, with matching ambig flags.
    newMomentProto.isSame = function (input, units) {
        var a;

        // only do custom logic if this is an enhanced moment
        if (!this._fullCalendar) {
            return oldMomentProto.isSame.apply(this, arguments);
        }

        if (units) {
            a = commonlyAmbiguate([this, input], true); // normalize timezones but don't erase times
            return oldMomentProto.isSame.call(a[0], a[1], units);
        } else {
            input = fc.moment.parseZone(input); // normalize input
            return oldMomentProto.isSame.call(this, input) &&
                    Boolean(this._ambigTime) === Boolean(input._ambigTime) &&
                    Boolean(this._ambigZone) === Boolean(input._ambigZone);
        }
    };

// Make these query methods work with ambiguous moments
    $.each([
        'isBefore',
        'isAfter'
    ], function (i, methodName) {
        newMomentProto[methodName] = function (input, units) {
            var a;

            // only do custom logic if this is an enhanced moment
            if (!this._fullCalendar) {
                return oldMomentProto[methodName].apply(this, arguments);
            }

            a = commonlyAmbiguate([this, input]);
            return oldMomentProto[methodName].call(a[0], a[1], units);
        };
    });


// Misc Internals
// -------------------------------------------------------------------------------------------------

// given an array of moment-like inputs, return a parallel array w/ moments similarly ambiguated.
// for example, of one moment has ambig time, but not others, all moments will have their time stripped.
// set `preserveTime` to `true` to keep times, but only normalize zone ambiguity.
// returns the original moments if no modifications are necessary.
    function commonlyAmbiguate(inputs, preserveTime) {
        var anyAmbigTime = false;
        var anyAmbigZone = false;
        var len = inputs.length;
        var moms = [];
        var i, mom;

        // parse inputs into real moments and query their ambig flags
        for (i = 0; i < len; i++) {
            mom = inputs[i];
            if (!moment.isMoment(mom)) {
                mom = fc.moment.parseZone(mom);
            }
            anyAmbigTime = anyAmbigTime || mom._ambigTime;
            anyAmbigZone = anyAmbigZone || mom._ambigZone;
            moms.push(mom);
        }

        // strip each moment down to lowest common ambiguity
        // use clones to avoid modifying the original moments
        for (i = 0; i < len; i++) {
            mom = moms[i];
            if (!preserveTime && anyAmbigTime && !mom._ambigTime) {
                moms[i] = mom.clone().stripTime();
            } else if (anyAmbigZone && !mom._ambigZone) {
                moms[i] = mom.clone().stripZone();
            }
        }

        return moms;
    }

// Transfers all the flags related to ambiguous time/zone from the `src` moment to the `dest` moment
    function transferAmbigs(src, dest) {
        if (src._ambigTime) {
            dest._ambigTime = true;
        } else if (dest._ambigTime) {
            dest._ambigTime = false;
        }

        if (src._ambigZone) {
            dest._ambigZone = true;
        } else if (dest._ambigZone) {
            dest._ambigZone = false;
        }
    }


// Sets the year/month/date/etc values of the moment from the given array.
// Inefficient because it calls each individual setter.
    function setMomentValues(mom, a) {
        mom.year(a[0] || 0)
                .month(a[1] || 0)
                .date(a[2] || 0)
                .hours(a[3] || 0)
                .minutes(a[4] || 0)
                .seconds(a[5] || 0)
                .milliseconds(a[6] || 0);
    }

// Can we set the moment's internal date directly?
    allowValueOptimization = '_d' in moment() && 'updateOffset' in moment;

// Utility function. Accepts a moment and an array of the UTC year/month/date/etc values to set.
// Assumes the given moment is already in UTC mode.
    setUTCValues = allowValueOptimization ? function (mom, a) {
        // simlate what moment's accessors do
        mom._d.setTime(Date.UTC.apply(Date, a));
        moment.updateOffset(mom, false); // keepTime=false
    } : setMomentValues;

// Utility function. Accepts a moment and an array of the local year/month/date/etc values to set.
// Assumes the given moment is already in local mode.
    setLocalValues = allowValueOptimization ? function (mom, a) {
        // simlate what moment's accessors do
        mom._d.setTime(+new Date(// FYI, there is now way to apply an array of args to a constructor
                a[0] || 0,
                a[1] || 0,
                a[2] || 0,
                a[3] || 0,
                a[4] || 0,
                a[5] || 0,
                a[6] || 0
                ));
        moment.updateOffset(mom, false); // keepTime=false
    } : setMomentValues;

// Single Date Formatting
// -------------------------------------------------------------------------------------------------


// call this if you want Moment's original format method to be used
    function oldMomentFormat(mom, formatStr) {
        return oldMomentProto.format.call(mom, formatStr); // oldMomentProto defined in moment-ext.js
    }


// Formats `date` with a Moment formatting string, but allow our non-zero areas and
// additional token.
    function formatDate(date, formatStr) {
        return formatDateWithChunks(date, getFormatStringChunks(formatStr));
    }


    function formatDateWithChunks(date, chunks) {
        var s = '';
        var i;

        for (i = 0; i < chunks.length; i++) {
            s += formatDateWithChunk(date, chunks[i]);
        }

        return s;
    }


// addition formatting tokens we want recognized
    var tokenOverrides = {
        t: function (date) { // "a" or "p"
            return oldMomentFormat(date, 'a').charAt(0);
        },
        T: function (date) { // "A" or "P"
            return oldMomentFormat(date, 'A').charAt(0);
        }
    };


    function formatDateWithChunk(date, chunk) {
        var token;
        var maybeStr;

        if (typeof chunk === 'string') { // a literal string
            return chunk;
        } else if ((token = chunk.token)) { // a token, like "YYYY"
            if (tokenOverrides[token]) {
                return tokenOverrides[token](date); // use our custom token
            }
            return oldMomentFormat(date, token);
        } else if (chunk.maybe) { // a grouping of other chunks that must be non-zero
            maybeStr = formatDateWithChunks(date, chunk.maybe);
            if (maybeStr.match(/[1-9]/)) {
                return maybeStr;
            }
        }

        return '';
    }


// Date Range Formatting
// -------------------------------------------------------------------------------------------------
// TODO: make it work with timezone offset

// Using a formatting string meant for a single date, generate a range string, like
// "Sep 2 - 9 2013", that intelligently inserts a separator where the dates differ.
// If the dates are the same as far as the format string is concerned, just return a single
// rendering of one date, without any separator.
    function formatRange(date1, date2, formatStr, separator, isRTL) {
        var localeData;

        date1 = fc.moment.parseZone(date1);
        date2 = fc.moment.parseZone(date2);

        localeData = (date1.localeData || date1.lang).call(date1); // works with moment-pre-2.8

        // Expand localized format strings, like "LL" -> "MMMM D YYYY"
        formatStr = localeData.longDateFormat(formatStr) || formatStr;
        // BTW, this is not important for `formatDate` because it is impossible to put custom tokens
        // or non-zero areas in Moment's localized format strings.

        separator = separator || ' - ';

        return formatRangeWithChunks(
                date1,
                date2,
                getFormatStringChunks(formatStr),
                separator,
                isRTL
                );
    }
    fc.formatRange = formatRange; // expose


    function formatRangeWithChunks(date1, date2, chunks, separator, isRTL) {
        var chunkStr; // the rendering of the chunk
        var leftI;
        var leftStr = '';
        var rightI;
        var rightStr = '';
        var middleI;
        var middleStr1 = '';
        var middleStr2 = '';
        var middleStr = '';

        // Start at the leftmost side of the formatting string and continue until you hit a token
        // that is not the same between dates.
        for (leftI = 0; leftI < chunks.length; leftI++) {
            chunkStr = formatSimilarChunk(date1, date2, chunks[leftI]);
            if (chunkStr === false) {
                break;
            }
            leftStr += chunkStr;
        }

        // Similarly, start at the rightmost side of the formatting string and move left
        for (rightI = chunks.length - 1; rightI > leftI; rightI--) {
            chunkStr = formatSimilarChunk(date1, date2, chunks[rightI]);
            if (chunkStr === false) {
                break;
            }
            rightStr = chunkStr + rightStr;
        }

        // The area in the middle is different for both of the dates.
        // Collect them distinctly so we can jam them together later.
        for (middleI = leftI; middleI <= rightI; middleI++) {
            middleStr1 += formatDateWithChunk(date1, chunks[middleI]);
            middleStr2 += formatDateWithChunk(date2, chunks[middleI]);
        }

        if (middleStr1 || middleStr2) {
            if (isRTL) {
                middleStr = middleStr2 + separator + middleStr1;
            } else {
                middleStr = middleStr1 + separator + middleStr2;
            }
        }

        return leftStr + middleStr + rightStr;
    }


    var similarUnitMap = {
        Y: 'year',
        M: 'month',
        D: 'day', // day of month
        d: 'day', // day of week
        // prevents a separator between anything time-related...
        A: 'second', // AM/PM
        a: 'second', // am/pm
        T: 'second', // A/P
        t: 'second', // a/p
        H: 'second', // hour (24)
        h: 'second', // hour (12)
        m: 'second', // minute
        s: 'second' // second
    };
// TODO: week maybe?


// Given a formatting chunk, and given that both dates are similar in the regard the
// formatting chunk is concerned, format date1 against `chunk`. Otherwise, return `false`.
    function formatSimilarChunk(date1, date2, chunk) {
        var token;
        var unit;

        if (typeof chunk === 'string') { // a literal string
            return chunk;
        } else if ((token = chunk.token)) {
            unit = similarUnitMap[token.charAt(0)];
            // are the dates the same for this unit of measurement?
            if (unit && date1.isSame(date2, unit)) {
                return oldMomentFormat(date1, token); // would be the same if we used `date2`
                // BTW, don't support custom tokens
            }
        }

        return false; // the chunk is NOT the same for the two dates
        // BTW, don't support splitting on non-zero areas
    }


// Chunking Utils
// -------------------------------------------------------------------------------------------------


    var formatStringChunkCache = {};


    function getFormatStringChunks(formatStr) {
        if (formatStr in formatStringChunkCache) {
            return formatStringChunkCache[formatStr];
        }
        return (formatStringChunkCache[formatStr] = chunkFormatString(formatStr));
    }


// Break the formatting string into an array of chunks
    function chunkFormatString(formatStr) {
        var chunks = [];
        var chunker = /\[([^\]]*)\]|\(([^\)]*)\)|(LT|(\w)\4*o?)|([^\w\[\(]+)/g; // TODO: more descrimination
        var match;

        while ((match = chunker.exec(formatStr))) {
            if (match[1]) { // a literal string inside [ ... ]
                chunks.push(match[1]);
            } else if (match[2]) { // non-zero formatting inside ( ... )
                chunks.push({maybe: chunkFormatString(match[2])});
            } else if (match[3]) { // a formatting token
                chunks.push({token: match[3]});
            } else if (match[5]) { // an unenclosed literal string
                chunks.push(match[5]);
            }
        }

        return chunks;
    }

    fc.Class = Class; // export

// class that all other classes will inherit from
    function Class() { }

// called upon a class to create a subclass
    Class.extend = function (members) {
        var superClass = this;
        var subClass;

        members = members || {};

        // ensure a constructor for the subclass, forwarding all arguments to the super-constructor if it doesn't exist
        if (hasOwnProp(members, 'constructor')) {
            subClass = members.constructor;
        }
        if (typeof subClass !== 'function') {
            subClass = members.constructor = function () {
                superClass.apply(this, arguments);
            };
        }

        // build the base prototype for the subclass, which is an new object chained to the superclass's prototype
        subClass.prototype = createObject(superClass.prototype);

        // copy each member variable/method onto the the subclass's prototype
        copyOwnProps(members, subClass.prototype);

        // copy over all class variables/methods to the subclass, such as `extend` and `mixin`
        copyOwnProps(superClass, subClass);

        return subClass;
    };

// adds new member variables/methods to the class's prototype.
// can be called with another class, or a plain object hash containing new members.
    Class.mixin = function (members) {
        copyOwnProps(members.prototype || members, this.prototype);
    };
    /* A rectangular panel that is absolutely positioned over other content
     ------------------------------------------------------------------------------------------------------------------------
     Options:
     - className (string)
     - content (HTML string or jQuery element set)
     - parentEl
     - top
     - left
     - right (the x coord of where the right edge should be. not a "CSS" right)
     - autoHide (boolean)
     - show (callback)
     - hide (callback)
     */

    var Popover = Class.extend({

        isHidden: true,
        options: null,
        el: null, // the container element for the popover. generated by this object
        documentMousedownProxy: null, // document mousedown handler bound to `this`
        margin: 10, // the space required between the popover and the edges of the scroll container


        constructor: function (options) {
            this.options = options || {};
        },

        // Shows the popover on the specified position. Renders it if not already
        show: function () {
            if (this.isHidden) {
                if (!this.el) {
                    this.render();
                }
                this.el.show();
                this.position();
                this.isHidden = false;
                this.trigger('show');
            }
        },

        // Hides the popover, through CSS, but does not remove it from the DOM
        hide: function () {
            if (!this.isHidden) {
                this.el.hide();
                this.isHidden = true;
                this.trigger('hide');
            }
        },

        // Creates `this.el` and renders content inside of it
        render: function () {
            var _this = this;
            var options = this.options;

            this.el = $('<div class="fc-popover"/>')
                    .addClass(options.className || '')
                    .css({
                        // position initially to the top left to avoid creating scrollbars
                        top: 0,
                        left: 0
                    })
                    .append(options.content)
                    .appendTo(options.parentEl);

            // when a click happens on anything inside with a 'fc-close' className, hide the popover
            this.el.on('click', '.fc-close', function () {
                _this.hide();
            });

            if (options.autoHide) {
                $(document).on('mousedown', this.documentMousedownProxy = $.proxy(this, 'documentMousedown'));
            }
        },

        // Triggered when the user clicks *anywhere* in the document, for the autoHide feature
        documentMousedown: function (ev) {
            // only hide the popover if the click happened outside the popover
            if (this.el && !$(ev.target).closest(this.el).length) {
                this.hide();
            }
        },

        // Hides and unregisters any handlers
        destroy: function () {
            this.hide();

            if (this.el) {
                this.el.remove();
                this.el = null;
            }

            $(document).off('mousedown', this.documentMousedownProxy);
        },

        // Positions the popover optimally, using the top/left/right options
        position: function () {
            var options = this.options;
            var origin = this.el.offsetParent().offset();
            var width = this.el.outerWidth();
            var height = this.el.outerHeight();
            var windowEl = $(window);
            var viewportEl = getScrollParent(this.el);
            var viewportTop;
            var viewportLeft;
            var viewportOffset;
            var top; // the "position" (not "offset") values for the popover
            var left; //

            // compute top and left
            top = options.top || 0;
            if (options.left !== undefined) {
                left = options.left;
            } else if (options.right !== undefined) {
                left = options.right - width; // derive the left value from the right value
            } else {
                left = 0;
            }

            if (viewportEl.is(window) || viewportEl.is(document)) { // normalize getScrollParent's result
                viewportEl = windowEl;
                viewportTop = 0; // the window is always at the top left
                viewportLeft = 0; // (and .offset() won't work if called here)
            } else {
                viewportOffset = viewportEl.offset();
                viewportTop = viewportOffset.top;
                viewportLeft = viewportOffset.left;
            }

            // if the window is scrolled, it causes the visible area to be further down
            viewportTop += windowEl.scrollTop();
            viewportLeft += windowEl.scrollLeft();

            // constrain to the view port. if constrained by two edges, give precedence to top/left
            if (options.viewportConstrain !== false) {
                top = Math.min(top, viewportTop + viewportEl.outerHeight() - height - this.margin);
                top = Math.max(top, viewportTop + this.margin);
                left = Math.min(left, viewportLeft + viewportEl.outerWidth() - width - this.margin);
                left = Math.max(left, viewportLeft + this.margin);
            }

            this.el.css({
                top: top - origin.top,
                left: left - origin.left
            });
        },

        // Triggers a callback. Calls a function in the option hash of the same name.
        // Arguments beyond the first `name` are forwarded on.
        // TODO: better code reuse for this. Repeat code
        trigger: function (name) {
            if (this.options[name]) {
                this.options[name].apply(this, Array.prototype.slice.call(arguments, 1));
            }
        }

    });

    /* A "coordinate map" converts pixel coordinates into an associated cell, which has an associated date
     ------------------------------------------------------------------------------------------------------------------------
     Common interface:
     
     CoordMap.prototype = {
     build: function() {},
     getCell: function(x, y) {}
     };
     
     */

    /* Coordinate map for a grid component
     ----------------------------------------------------------------------------------------------------------------------*/

    var GridCoordMap = Class.extend({

        grid: null, // reference to the Grid
        rowCoords: null, // array of {top,bottom} objects
        colCoords: null, // array of {left,right} objects

        containerEl: null, // container element that all coordinates are constrained to. optionally assigned
        minX: null,
        maxX: null, // exclusive
        minY: null,
        maxY: null, // exclusive


        constructor: function (grid) {
            this.grid = grid;
        },

        // Queries the grid for the coordinates of all the cells
        build: function () {
            this.rowCoords = this.grid.computeRowCoords();
            this.colCoords = this.grid.computeColCoords();
            this.computeBounds();
        },

        // Clears the coordinates data to free up memory
        clear: function () {
            this.rowCoords = null;
            this.colCoords = null;
        },

        // Given a coordinate of the document, gets the associated cell. If no cell is underneath, returns null
        getCell: function (x, y) {
            var rowCoords = this.rowCoords;
            var colCoords = this.colCoords;
            var hitRow = null;
            var hitCol = null;
            var i, coords;
            var cell;

            if (this.inBounds(x, y)) {

                for (i = 0; i < rowCoords.length; i++) {
                    coords = rowCoords[i];
                    if (y >= coords.top && y < coords.bottom) {
                        hitRow = i;
                        break;
                    }
                }

                for (i = 0; i < colCoords.length; i++) {
                    coords = colCoords[i];
                    if (x >= coords.left && x < coords.right) {
                        hitCol = i;
                        break;
                    }
                }

                if (hitRow !== null && hitCol !== null) {
                    cell = this.grid.getCell(hitRow, hitCol);
                    cell.grid = this.grid; // for DragListener's isCellsEqual. dragging between grids
                    return cell;
                }
            }

            return null;
        },

        // If there is a containerEl, compute the bounds into min/max values
        computeBounds: function () {
            var containerOffset;

            if (this.containerEl) {
                containerOffset = this.containerEl.offset();
                this.minX = containerOffset.left;
                this.maxX = containerOffset.left + this.containerEl.outerWidth();
                this.minY = containerOffset.top;
                this.maxY = containerOffset.top + this.containerEl.outerHeight();
            }
        },

        // Determines if the given coordinates are in bounds. If no `containerEl`, always true
        inBounds: function (x, y) {
            if (this.containerEl) {
                return x >= this.minX && x < this.maxX && y >= this.minY && y < this.maxY;
            }
            return true;
        }

    });


    /* Coordinate map that is a combination of multiple other coordinate maps
     ----------------------------------------------------------------------------------------------------------------------*/

    var ComboCoordMap = Class.extend({

        coordMaps: null, // an array of CoordMaps


        constructor: function (coordMaps) {
            this.coordMaps = coordMaps;
        },

        // Builds all coordMaps
        build: function () {
            var coordMaps = this.coordMaps;
            var i;

            for (i = 0; i < coordMaps.length; i++) {
                coordMaps[i].build();
            }
        },

        // Queries all coordMaps for the cell underneath the given coordinates, returning the first result
        getCell: function (x, y) {
            var coordMaps = this.coordMaps;
            var cell = null;
            var i;

            for (i = 0; i < coordMaps.length && !cell; i++) {
                cell = coordMaps[i].getCell(x, y);
            }

            return cell;
        },

        // Clears all coordMaps
        clear: function () {
            var coordMaps = this.coordMaps;
            var i;

            for (i = 0; i < coordMaps.length; i++) {
                coordMaps[i].clear();
            }
        }

    });

    /* Tracks mouse movements over a CoordMap and raises events about which cell the mouse is over.
     ----------------------------------------------------------------------------------------------------------------------*/
// TODO: very useful to have a handler that gets called upon cellOut OR when dragging stops (for cleanup)

    var DragListener = Class.extend({

        coordMap: null,
        options: null,

        isListening: false,
        isDragging: false,

        // the cell the mouse was over when listening started
        origCell: null,

        // the cell the mouse is over
        cell: null,

        // coordinates of the initial mousedown
        mouseX0: null,
        mouseY0: null,

        // handler attached to the document, bound to the DragListener's `this`
        mousemoveProxy: null,
        mouseupProxy: null,

        scrollEl: null,
        scrollBounds: null, // { top, bottom, left, right }
        scrollTopVel: null, // pixels per second
        scrollLeftVel: null, // pixels per second
        scrollIntervalId: null, // ID of setTimeout for scrolling animation loop
        scrollHandlerProxy: null, // this-scoped function for handling when scrollEl is scrolled

        scrollSensitivity: 30, // pixels from edge for scrolling to start
        scrollSpeed: 200, // pixels per second, at maximum speed
        scrollIntervalMs: 50, // millisecond wait between scroll increment


        constructor: function (coordMap, options) {
            this.coordMap = coordMap;
            this.options = options || {};
        },

        // Call this when the user does a mousedown. Will probably lead to startListening
        mousedown: function (ev) {
            if (isPrimaryMouseButton(ev)) {

                ev.preventDefault(); // prevents native selection in most browsers

                this.startListening(ev);

                // start the drag immediately if there is no minimum distance for a drag start
                if (!this.options.distance) {
                    this.startDrag(ev);
                }
            }
        },

        // Call this to start tracking mouse movements
        startListening: function (ev) {
            var scrollParent;
            var cell;

            if (!this.isListening) {

                // grab scroll container and attach handler
                if (ev && this.options.scroll) {
                    scrollParent = getScrollParent($(ev.target));
                    if (!scrollParent.is(window) && !scrollParent.is(document)) {
                        this.scrollEl = scrollParent;

                        // scope to `this`, and use `debounce` to make sure rapid calls don't happen
                        this.scrollHandlerProxy = debounce($.proxy(this, 'scrollHandler'), 100);
                        this.scrollEl.on('scroll', this.scrollHandlerProxy);
                    }
                }

                this.computeCoords(); // relies on `scrollEl`

                // get info on the initial cell and its coordinates
                if (ev) {
                    cell = this.getCell(ev);
                    this.origCell = cell;

                    this.mouseX0 = ev.pageX;
                    this.mouseY0 = ev.pageY;
                }

                $(document)
                        .on('mousemove', this.mousemoveProxy = $.proxy(this, 'mousemove'))
                        .on('mouseup', this.mouseupProxy = $.proxy(this, 'mouseup'))
                        .on('selectstart', this.preventDefault); // prevents native selection in IE<=8

                this.isListening = true;
                this.trigger('listenStart', ev);
            }
        },

        // Recomputes the drag-critical positions of elements
        computeCoords: function () {
            this.coordMap.build();
            this.computeScrollBounds();
        },

        // Called when the user moves the mouse
        mousemove: function (ev) {
            var minDistance;
            var distanceSq; // current distance from mouseX0/mouseY0, squared

            if (!this.isDragging) { // if not already dragging...
                // then start the drag if the minimum distance criteria is met
                minDistance = this.options.distance || 1;
                distanceSq = Math.pow(ev.pageX - this.mouseX0, 2) + Math.pow(ev.pageY - this.mouseY0, 2);
                if (distanceSq >= minDistance * minDistance) { // use pythagorean theorem
                    this.startDrag(ev);
                }
            }

            if (this.isDragging) {
                this.drag(ev); // report a drag, even if this mousemove initiated the drag
            }
        },

        // Call this to initiate a legitimate drag.
        // This function is called internally from this class, but can also be called explicitly from outside
        startDrag: function (ev) {
            var cell;

            if (!this.isListening) { // startDrag must have manually initiated
                this.startListening();
            }

            if (!this.isDragging) {
                this.isDragging = true;
                this.trigger('dragStart', ev);

                // report the initial cell the mouse is over
                // especially important if no min-distance and drag starts immediately
                cell = this.getCell(ev); // this might be different from this.origCell if the min-distance is large
                if (cell) {
                    this.cellOver(cell);
                }
            }
        },

        // Called while the mouse is being moved and when we know a legitimate drag is taking place
        drag: function (ev) {
            var cell;

            if (this.isDragging) {
                cell = this.getCell(ev);

                if (!isCellsEqual(cell, this.cell)) { // a different cell than before?
                    if (this.cell) {
                        this.cellOut();
                    }
                    if (cell) {
                        this.cellOver(cell);
                    }
                }

                this.dragScroll(ev); // will possibly cause scrolling
            }
        },

        // Called when a the mouse has just moved over a new cell
        cellOver: function (cell) {
            this.cell = cell;
            this.trigger('cellOver', cell, isCellsEqual(cell, this.origCell));
        },

        // Called when the mouse has just moved out of a cell
        cellOut: function () {
            if (this.cell) {
                this.trigger('cellOut', this.cell);
                this.cell = null;
            }
        },

        // Called when the user does a mouseup
        mouseup: function (ev) {
            this.stopDrag(ev);
            this.stopListening(ev);
        },

        // Called when the drag is over. Will not cause listening to stop however.
        // A concluding 'cellOut' event will NOT be triggered.
        stopDrag: function (ev) {
            if (this.isDragging) {
                this.stopScrolling();
                this.trigger('dragStop', ev);
                this.isDragging = false;
            }
        },

        // Call this to stop listening to the user's mouse events
        stopListening: function (ev) {
            if (this.isListening) {

                // remove the scroll handler if there is a scrollEl
                if (this.scrollEl) {
                    this.scrollEl.off('scroll', this.scrollHandlerProxy);
                    this.scrollHandlerProxy = null;
                }

                $(document)
                        .off('mousemove', this.mousemoveProxy)
                        .off('mouseup', this.mouseupProxy)
                        .off('selectstart', this.preventDefault);

                this.mousemoveProxy = null;
                this.mouseupProxy = null;

                this.isListening = false;
                this.trigger('listenStop', ev);

                this.origCell = this.cell = null;
                this.coordMap.clear();
            }
        },

        // Gets the cell underneath the coordinates for the given mouse event
        getCell: function (ev) {
            return this.coordMap.getCell(ev.pageX, ev.pageY);
        },

        // Triggers a callback. Calls a function in the option hash of the same name.
        // Arguments beyond the first `name` are forwarded on.
        trigger: function (name) {
            if (this.options[name]) {
                this.options[name].apply(this, Array.prototype.slice.call(arguments, 1));
            }
        },

        // Stops a given mouse event from doing it's native browser action. In our case, text selection.
        preventDefault: function (ev) {
            ev.preventDefault();
        },

        /* Scrolling
         ------------------------------------------------------------------------------------------------------------------*/


        // Computes and stores the bounding rectangle of scrollEl
        computeScrollBounds: function () {
            var el = this.scrollEl;
            var offset;

            if (el) {
                offset = el.offset();
                this.scrollBounds = {
                    top: offset.top,
                    left: offset.left,
                    bottom: offset.top + el.outerHeight(),
                    right: offset.left + el.outerWidth()
                };
            }
        },

        // Called when the dragging is in progress and scrolling should be updated
        dragScroll: function (ev) {
            var sensitivity = this.scrollSensitivity;
            var bounds = this.scrollBounds;
            var topCloseness, bottomCloseness;
            var leftCloseness, rightCloseness;
            var topVel = 0;
            var leftVel = 0;

            if (bounds) { // only scroll if scrollEl exists

                // compute closeness to edges. valid range is from 0.0 - 1.0
                topCloseness = (sensitivity - (ev.pageY - bounds.top)) / sensitivity;
                bottomCloseness = (sensitivity - (bounds.bottom - ev.pageY)) / sensitivity;
                leftCloseness = (sensitivity - (ev.pageX - bounds.left)) / sensitivity;
                rightCloseness = (sensitivity - (bounds.right - ev.pageX)) / sensitivity;

                // translate vertical closeness into velocity.
                // mouse must be completely in bounds for velocity to happen.
                if (topCloseness >= 0 && topCloseness <= 1) {
                    topVel = topCloseness * this.scrollSpeed * -1; // negative. for scrolling up
                } else if (bottomCloseness >= 0 && bottomCloseness <= 1) {
                    topVel = bottomCloseness * this.scrollSpeed;
                }

                // translate horizontal closeness into velocity
                if (leftCloseness >= 0 && leftCloseness <= 1) {
                    leftVel = leftCloseness * this.scrollSpeed * -1; // negative. for scrolling left
                } else if (rightCloseness >= 0 && rightCloseness <= 1) {
                    leftVel = rightCloseness * this.scrollSpeed;
                }
            }

            this.setScrollVel(topVel, leftVel);
        },

        // Sets the speed-of-scrolling for the scrollEl
        setScrollVel: function (topVel, leftVel) {

            this.scrollTopVel = topVel;
            this.scrollLeftVel = leftVel;

            this.constrainScrollVel(); // massages into realistic values

            // if there is non-zero velocity, and an animation loop hasn't already started, then START
            if ((this.scrollTopVel || this.scrollLeftVel) && !this.scrollIntervalId) {
                this.scrollIntervalId = setInterval(
                        $.proxy(this, 'scrollIntervalFunc'), // scope to `this`
                        this.scrollIntervalMs
                        );
            }
        },

        // Forces scrollTopVel and scrollLeftVel to be zero if scrolling has already gone all the way
        constrainScrollVel: function () {
            var el = this.scrollEl;

            if (this.scrollTopVel < 0) { // scrolling up?
                if (el.scrollTop() <= 0) { // already scrolled all the way up?
                    this.scrollTopVel = 0;
                }
            } else if (this.scrollTopVel > 0) { // scrolling down?
                if (el.scrollTop() + el[0].clientHeight >= el[0].scrollHeight) { // already scrolled all the way down?
                    this.scrollTopVel = 0;
                }
            }

            if (this.scrollLeftVel < 0) { // scrolling left?
                if (el.scrollLeft() <= 0) { // already scrolled all the left?
                    this.scrollLeftVel = 0;
                }
            } else if (this.scrollLeftVel > 0) { // scrolling right?
                if (el.scrollLeft() + el[0].clientWidth >= el[0].scrollWidth) { // already scrolled all the way right?
                    this.scrollLeftVel = 0;
                }
            }
        },

        // This function gets called during every iteration of the scrolling animation loop
        scrollIntervalFunc: function () {
            var el = this.scrollEl;
            var frac = this.scrollIntervalMs / 1000; // considering animation frequency, what the vel should be mult'd by

            // change the value of scrollEl's scroll
            if (this.scrollTopVel) {
                el.scrollTop(el.scrollTop() + this.scrollTopVel * frac);
            }
            if (this.scrollLeftVel) {
                el.scrollLeft(el.scrollLeft() + this.scrollLeftVel * frac);
            }

            this.constrainScrollVel(); // since the scroll values changed, recompute the velocities

            // if scrolled all the way, which causes the vels to be zero, stop the animation loop
            if (!this.scrollTopVel && !this.scrollLeftVel) {
                this.stopScrolling();
            }
        },

        // Kills any existing scrolling animation loop
        stopScrolling: function () {
            if (this.scrollIntervalId) {
                clearInterval(this.scrollIntervalId);
                this.scrollIntervalId = null;

                // when all done with scrolling, recompute positions since they probably changed
                this.computeCoords();
            }
        },

        // Get called when the scrollEl is scrolled (NOTE: this is delayed via debounce)
        scrollHandler: function () {
            // recompute all coordinates, but *only* if this is *not* part of our scrolling animation
            if (!this.scrollIntervalId) {
                this.computeCoords();
            }
        }

    });


// Returns `true` if the cells are identically equal. `false` otherwise.
// They must have the same row, col, and be from the same grid.
// Two null values will be considered equal, as two "out of the grid" states are the same.
    function isCellsEqual(cell1, cell2) {

        if (!cell1 && !cell2) {
            return true;
        }

        if (cell1 && cell2) {
            return cell1.grid === cell2.grid &&
                    cell1.row === cell2.row &&
                    cell1.col === cell2.col;
        }

        return false;
    }

    /* Creates a clone of an element and lets it track the mouse as it moves
     ----------------------------------------------------------------------------------------------------------------------*/

    var MouseFollower = Class.extend({

        options: null,

        sourceEl: null, // the element that will be cloned and made to look like it is dragging
        el: null, // the clone of `sourceEl` that will track the mouse
        parentEl: null, // the element that `el` (the clone) will be attached to

        // the initial position of el, relative to the offset parent. made to match the initial offset of sourceEl
        top0: null,
        left0: null,

        // the initial position of the mouse
        mouseY0: null,
        mouseX0: null,

        // the number of pixels the mouse has moved from its initial position
        topDelta: null,
        leftDelta: null,

        mousemoveProxy: null, // document mousemove handler, bound to the MouseFollower's `this`

        isFollowing: false,
        isHidden: false,
        isAnimating: false, // doing the revert animation?

        constructor: function (sourceEl, options) {
            this.options = options = options || {};
            this.sourceEl = sourceEl;
            this.parentEl = options.parentEl ? $(options.parentEl) : sourceEl.parent(); // default to sourceEl's parent
        },

        // Causes the element to start following the mouse
        start: function (ev) {
            if (!this.isFollowing) {
                this.isFollowing = true;

                this.mouseY0 = ev.pageY;
                this.mouseX0 = ev.pageX;
                this.topDelta = 0;
                this.leftDelta = 0;

                if (!this.isHidden) {
                    this.updatePosition();
                }

                $(document).on('mousemove', this.mousemoveProxy = $.proxy(this, 'mousemove'));
            }
        },

        // Causes the element to stop following the mouse. If shouldRevert is true, will animate back to original position.
        // `callback` gets invoked when the animation is complete. If no animation, it is invoked immediately.
        stop: function (shouldRevert, callback) {
            var _this = this;
            var revertDuration = this.options.revertDuration;

            function complete() {
                this.isAnimating = false;
                _this.destroyEl();

                this.top0 = this.left0 = null; // reset state for future updatePosition calls

                if (callback) {
                    callback();
                }
            }

            if (this.isFollowing && !this.isAnimating) { // disallow more than one stop animation at a time
                this.isFollowing = false;

                $(document).off('mousemove', this.mousemoveProxy);

                if (shouldRevert && revertDuration && !this.isHidden) { // do a revert animation?
                    this.isAnimating = true;
                    this.el.animate({
                        top: this.top0,
                        left: this.left0
                    }, {
                        duration: revertDuration,
                        complete: complete
                    });
                } else {
                    complete();
                }
            }
        },

        // Gets the tracking element. Create it if necessary
        getEl: function () {
            var el = this.el;

            if (!el) {
                this.sourceEl.width(); // hack to force IE8 to compute correct bounding box
                el = this.el = this.sourceEl.clone()
                        .css({
                            position: 'absolute',
                            visibility: '', // in case original element was hidden (commonly through hideEvents())
                            display: this.isHidden ? 'none' : '', // for when initially hidden
                            margin: 0,
                            right: 'auto', // erase and set width instead
                            bottom: 'auto', // erase and set height instead
                            width: this.sourceEl.width(), // explicit height in case there was a 'right' value
                            height: this.sourceEl.height(), // explicit width in case there was a 'bottom' value
                            opacity: this.options.opacity || '',
                            zIndex: this.options.zIndex
                        })
                        .appendTo(this.parentEl);
            }

            return el;
        },

        // Removes the tracking element if it has already been created
        destroyEl: function () {
            if (this.el) {
                this.el.remove();
                this.el = null;
            }
        },

        // Update the CSS position of the tracking element
        updatePosition: function () {
            var sourceOffset;
            var origin;

            this.getEl(); // ensure this.el

            // make sure origin info was computed
            if (this.top0 === null) {
                this.sourceEl.width(); // hack to force IE8 to compute correct bounding box
                sourceOffset = this.sourceEl.offset();
                origin = this.el.offsetParent().offset();
                this.top0 = sourceOffset.top - origin.top;
                this.left0 = sourceOffset.left - origin.left;
            }

            this.el.css({
                top: this.top0 + this.topDelta,
                left: this.left0 + this.leftDelta
            });
        },

        // Gets called when the user moves the mouse
        mousemove: function (ev) {
            this.topDelta = ev.pageY - this.mouseY0;
            this.leftDelta = ev.pageX - this.mouseX0;

            if (!this.isHidden) {
                this.updatePosition();
            }
        },

        // Temporarily makes the tracking element invisible. Can be called before following starts
        hide: function () {
            if (!this.isHidden) {
                this.isHidden = true;
                if (this.el) {
                    this.el.hide();
                }
            }
        },

        // Show the tracking element after it has been temporarily hidden
        show: function () {
            if (this.isHidden) {
                this.isHidden = false;
                this.updatePosition();
                this.getEl().show();
            }
        }

    });

    /* A utility class for rendering <tr> rows.
     ----------------------------------------------------------------------------------------------------------------------*/
// It leverages methods of the subclass and the View to determine custom rendering behavior for each row "type"
// (such as highlight rows, day rows, helper rows, etc).

    var RowRenderer = Class.extend({

        view: null, // a View object
        isRTL: null, // shortcut to the view's isRTL option
        cellHtml: '<td/>', // plain default HTML used for a cell when no other is available


        constructor: function (view) {
            this.view = view;
            this.isRTL = view.opt('isRTL');
        },

        // Renders the HTML for a row, leveraging custom cell-HTML-renderers based on the `rowType`.
        // Also applies the "intro" and "outro" cells, which are specified by the subclass and views.
        // `row` is an optional row number.
        rowHtml: function (rowType, row) {
            var renderCell = this.getHtmlRenderer('cell', rowType);
            var rowCellHtml = '';
            var col;
            var cell;

            row = row || 0;

            for (col = 0; col < this.colCnt; col++) {
                cell = this.getCell(row, col);
                rowCellHtml += renderCell(cell);
            }

            rowCellHtml = this.bookendCells(rowCellHtml, rowType, row); // apply intro and outro

            return '<tr>' + rowCellHtml + '</tr>';
        },

        // Applies the "intro" and "outro" HTML to the given cells.
        // Intro means the leftmost cell when the calendar is LTR and the rightmost cell when RTL. Vice-versa for outro.
        // `cells` can be an HTML string of <td>'s or a jQuery <tr> element
        // `row` is an optional row number.
        bookendCells: function (cells, rowType, row) {
            var intro = this.getHtmlRenderer('intro', rowType)(row || 0);
            var outro = this.getHtmlRenderer('outro', rowType)(row || 0);
            var prependHtml = this.isRTL ? outro : intro;
            var appendHtml = this.isRTL ? intro : outro;

            if (typeof cells === 'string') {
                return prependHtml + cells + appendHtml;
            } else { // a jQuery <tr> element
                return cells.prepend(prependHtml).append(appendHtml);
            }
        },

        // Returns an HTML-rendering function given a specific `rendererName` (like cell, intro, or outro) and a specific
        // `rowType` (like day, eventSkeleton, helperSkeleton), which is optional.
        // If a renderer for the specific rowType doesn't exist, it will fall back to a generic renderer.
        // We will query the View object first for any custom rendering functions, then the methods of the subclass.
        getHtmlRenderer: function (rendererName, rowType) {
            var view = this.view;
            var generalName; // like "cellHtml"
            var specificName; // like "dayCellHtml". based on rowType
            var provider; // either the View or the RowRenderer subclass, whichever provided the method
            var renderer;

            generalName = rendererName + 'Html';
            if (rowType) {
                specificName = rowType + capitaliseFirstLetter(rendererName) + 'Html';
            }

            if (specificName && (renderer = view[specificName])) {
                provider = view;
            } else if (specificName && (renderer = this[specificName])) {
                provider = this;
            } else if ((renderer = view[generalName])) {
                provider = view;
            } else if ((renderer = this[generalName])) {
                provider = this;
            }

            if (typeof renderer === 'function') {
                return function () {
                    return renderer.apply(provider, arguments) || ''; // use correct `this` and always return a string
                };
            }

            // the rendered can be a plain string as well. if not specified, always an empty string.
            return function () {
                return renderer || '';
            };
        }

    });

    /* An abstract class comprised of a "grid" of cells that each represent a specific datetime
     ----------------------------------------------------------------------------------------------------------------------*/

    var Grid = fc.Grid = RowRenderer.extend({

        start: null, // the date of the first cell
        end: null, // the date after the last cell

        rowCnt: 0, // number of rows
        colCnt: 0, // number of cols
        rowData: null, // array of objects, holding misc data for each row
        colData: null, // array of objects, holding misc data for each column

        el: null, // the containing element
        coordMap: null, // a GridCoordMap that converts pixel values to datetimes
        elsByFill: null, // a hash of jQuery element sets used for rendering each fill. Keyed by fill name.

        documentDragStartProxy: null, // binds the Grid's scope to documentDragStart (in DayGrid.events)

        // derived from options
        colHeadFormat: null, // TODO: move to another class. not applicable to all Grids
        eventTimeFormat: null,
        displayEventEnd: null,

        constructor: function () {
            RowRenderer.apply(this, arguments); // call the super-constructor

            this.coordMap = new GridCoordMap(this);
            this.elsByFill = {};
            this.documentDragStartProxy = $.proxy(this, 'documentDragStart');
        },

        // Renders the grid into the `el` element.
        // Subclasses should override and call this super-method when done.
        render: function () {
            this.bindHandlers();
        },

        // Called when the grid's resources need to be cleaned up
        destroy: function () {
            this.unbindHandlers();
        },

        /* Options
         ------------------------------------------------------------------------------------------------------------------*/


        // Generates the format string used for the text in column headers, if not explicitly defined by 'columnFormat'
        // TODO: move to another class. not applicable to all Grids
        computeColHeadFormat: function () {
            // subclasses must implement if they want to use headHtml()
        },

        // Generates the format string used for event time text, if not explicitly defined by 'timeFormat'
        computeEventTimeFormat: function () {
            return this.view.opt('smallTimeFormat');
        },

        // Determines whether events should have their end times displayed, if not explicitly defined by 'displayEventEnd'
        computeDisplayEventEnd: function () {
            return false;
        },

        /* Dates
         ------------------------------------------------------------------------------------------------------------------*/


        // Tells the grid about what period of time to display. Grid will subsequently compute dates for cell system.
        setRange: function (range) {
            var view = this.view;

            this.start = range.start.clone();
            this.end = range.end.clone();

            this.rowData = [];
            this.colData = [];
            this.updateCells();

            // Populate option-derived settings. Look for override first, then compute if necessary.
            this.colHeadFormat = view.opt('columnFormat') || this.computeColHeadFormat();
            this.eventTimeFormat = view.opt('timeFormat') || this.computeEventTimeFormat();
            this.displayEventEnd = view.opt('displayEventEnd');
            if (this.displayEventEnd == null) {
                this.displayEventEnd = this.computeDisplayEventEnd();
            }
        },

        // Responsible for setting rowCnt/colCnt and any other row/col data
        updateCells: function () {
            // subclasses must implement
        },

        // Converts a range with an inclusive `start` and an exclusive `end` into an array of segment objects
        rangeToSegs: function (range) {
            // subclasses must implement
        },

        /* Cells
         ------------------------------------------------------------------------------------------------------------------*/
        // NOTE: columns are ordered left-to-right


        // Gets an object containing row/col number, misc data, and range information about the cell.
        // Accepts row/col values, an object with row/col properties, or a single-number offset from the first cell.
        getCell: function (row, col) {
            var cell;

            if (col == null) {
                if (typeof row === 'number') { // a single-number offset
                    col = row % this.colCnt;
                    row = Math.floor(row / this.colCnt);
                } else { // an object with row/col properties
                    col = row.col;
                    row = row.row;
                }
            }

            cell = {row: row, col: col};

            $.extend(cell, this.getRowData(row), this.getColData(col));
            $.extend(cell, this.computeCellRange(cell));

            return cell;
        },

        // Given a cell object with index and misc data, generates a range object
        computeCellRange: function (cell) {
            // subclasses must implement
        },

        // Retrieves misc data about the given row
        getRowData: function (row) {
            return this.rowData[row] || {};
        },

        // Retrieves misc data baout the given column
        getColData: function (col) {
            return this.colData[col] || {};
        },

        // Retrieves the element representing the given row
        getRowEl: function (row) {
            // subclasses should implement if leveraging the default getCellDayEl() or computeRowCoords()
        },

        // Retrieves the element representing the given column
        getColEl: function (col) {
            // subclasses should implement if leveraging the default getCellDayEl() or computeColCoords()
        },

        // Given a cell object, returns the element that represents the cell's whole-day
        getCellDayEl: function (cell) {
            return this.getColEl(cell.col) || this.getRowEl(cell.row);
        },

        /* Cell Coordinates
         ------------------------------------------------------------------------------------------------------------------*/


        // Computes the top/bottom coordinates of all rows.
        // By default, queries the dimensions of the element provided by getRowEl().
        computeRowCoords: function () {
            var items = [];
            var i, el;
            var item;

            for (i = 0; i < this.rowCnt; i++) {
                el = this.getRowEl(i);
                item = {
                    top: el.offset().top
                };
                if (i > 0) {
                    items[i - 1].bottom = item.top;
                }
                items.push(item);
            }
            item.bottom = item.top + el.outerHeight();

            return items;
        },

        // Computes the left/right coordinates of all rows.
        // By default, queries the dimensions of the element provided by getColEl().
        computeColCoords: function () {
            var items = [];
            var i, el;
            var item;

            for (i = 0; i < this.colCnt; i++) {
                el = this.getColEl(i);
                item = {
                    left: el.offset().left
                };
                if (i > 0) {
                    items[i - 1].right = item.left;
                }
                items.push(item);
            }
            item.right = item.left + el.outerWidth();

            return items;
        },

        /* Handlers
         ------------------------------------------------------------------------------------------------------------------*/


        // Attaches handlers to DOM
        bindHandlers: function () {
            var _this = this;

            // attach a handler to the grid's root element.
            // we don't need to clean up in unbindHandlers or destroy, because when jQuery removes the element from the
            // DOM it automatically unregisters the handlers.
            this.el.on('mousedown', function (ev) {
                if (
                        !$(ev.target).is('.fc-event-container *, .fc-more') && // not an an event element, or "more.." link
                        !$(ev.target).closest('.fc-popover').length // not on a popover (like the "more.." events one)
                        ) {
                    _this.dayMousedown(ev);
                }
            });

            // attach event-element-related handlers. in Grid.events
            // same garbage collection note as above.
            this.bindSegHandlers();

            $(document).on('dragstart', this.documentDragStartProxy); // jqui drag
        },

        // Unattaches handlers from the DOM
        unbindHandlers: function () {
            $(document).off('dragstart', this.documentDragStartProxy); // jqui drag
        },

        // Process a mousedown on an element that represents a day. For day clicking and selecting.
        dayMousedown: function (ev) {
            var _this = this;
            var view = this.view;
            var isSelectable = view.opt('selectable');
            var dayClickCell; // null if invalid dayClick
            var selectionRange; // null if invalid selection

            // this listener tracks a mousedown on a day element, and a subsequent drag.
            // if the drag ends on the same day, it is a 'dayClick'.
            // if 'selectable' is enabled, this listener also detects selections.
            var dragListener = new DragListener(this.coordMap, {
                //distance: 5, // needs more work if we want dayClick to fire correctly
                scroll: view.opt('dragScroll'),
                dragStart: function () {
                    view.unselect(); // since we could be rendering a new selection, we want to clear any old one
                },
                cellOver: function (cell, isOrig) {
                    var origCell = dragListener.origCell;
                    if (origCell) { // click needs to have started on a cell
                        dayClickCell = isOrig ? cell : null; // single-cell selection is a day click
                        if (isSelectable) {
                            selectionRange = _this.computeSelection(origCell, cell);
                            if (selectionRange) {
                                _this.renderSelection(selectionRange);
                            } else {
                                disableCursor();
                            }
                        }
                    }
                },
                cellOut: function (cell) {
                    dayClickCell = null;
                    selectionRange = null;
                    _this.destroySelection();
                    enableCursor();
                },
                listenStop: function (ev) {
                    if (dayClickCell) {
                        view.trigger('dayClick', _this.getCellDayEl(dayClickCell), dayClickCell.start, ev);
                    }
                    if (selectionRange) {
                        // the selection will already have been rendered. just report it
                        view.reportSelection(selectionRange, ev);
                    }
                    enableCursor();
                }
            });

            dragListener.mousedown(ev); // start listening, which will eventually initiate a dragStart
        },

        /* Event Helper
         ------------------------------------------------------------------------------------------------------------------*/
        // TODO: should probably move this to Grid.events, like we did event dragging / resizing


        // Renders a mock event over the given range.
        // The range's end can be null, in which case the mock event that is rendered will have a null end time.
        // `sourceSeg` is the internal segment object involved in the drag. If null, something external is dragging.
        renderRangeHelper: function (range, sourceSeg) {
            var fakeEvent;

            fakeEvent = sourceSeg ? createObject(sourceSeg.event) : {}; // mask the original event object if possible
            fakeEvent.start = range.start.clone();
            fakeEvent.end = range.end ? range.end.clone() : null;
            fakeEvent.allDay = null; // force it to be freshly computed by normalizeEventDateProps
            this.view.calendar.normalizeEventDateProps(fakeEvent);

            // this extra className will be useful for differentiating real events from mock events in CSS
            fakeEvent.className = (fakeEvent.className || []).concat('fc-helper');

            // if something external is being dragged in, don't render a resizer
            if (!sourceSeg) {
                fakeEvent.editable = false;
            }

            this.renderHelper(fakeEvent, sourceSeg); // do the actual rendering
        },

        // Renders a mock event
        renderHelper: function (event, sourceSeg) {
            // subclasses must implement
        },

        // Unrenders a mock event
        destroyHelper: function () {
            // subclasses must implement
        },

        /* Selection
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a visual indication of a selection. Will highlight by default but can be overridden by subclasses.
        renderSelection: function (range) {
            this.renderHighlight(range);
        },

        // Unrenders any visual indications of a selection. Will unrender a highlight by default.
        destroySelection: function () {
            this.destroyHighlight();
        },

        // Given the first and last cells of a selection, returns a range object.
        // Will return something falsy if the selection is invalid (when outside of selectionConstraint for example).
        // Subclasses can override and provide additional data in the range object. Will be passed to renderSelection().
        computeSelection: function (firstCell, lastCell) {
            var dates = [
                firstCell.start,
                firstCell.end,
                lastCell.start,
                lastCell.end
            ];
            var range;

            dates.sort(compareNumbers); // sorts chronologically. works with Moments

            range = {
                start: dates[0].clone(),
                end: dates[3].clone()
            };

            if (!this.view.calendar.isSelectionRangeAllowed(range)) {
                return null;
            }

            return range;
        },

        /* Highlight
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders an emphasis on the given date range. `start` is inclusive. `end` is exclusive.
        renderHighlight: function (range) {
            this.renderFill('highlight', this.rangeToSegs(range));
        },

        // Unrenders the emphasis on a date range
        destroyHighlight: function () {
            this.destroyFill('highlight');
        },

        // Generates an array of classNames for rendering the highlight. Used by the fill system.
        highlightSegClasses: function () {
            return ['fc-highlight'];
        },

        /* Fill System (highlight, background events, business hours)
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a set of rectangles over the given segments of time.
        // Returns a subset of segs, the segs that were actually rendered.
        // Responsible for populating this.elsByFill. TODO: better API for expressing this requirement
        renderFill: function (type, segs) {
            // subclasses must implement
        },

        // Unrenders a specific type of fill that is currently rendered on the grid
        destroyFill: function (type) {
            var el = this.elsByFill[type];

            if (el) {
                el.remove();
                delete this.elsByFill[type];
            }
        },

        // Renders and assigns an `el` property for each fill segment. Generic enough to work with different types.
        // Only returns segments that successfully rendered.
        // To be harnessed by renderFill (implemented by subclasses).
        // Analagous to renderFgSegEls.
        renderFillSegEls: function (type, segs) {
            var _this = this;
            var segElMethod = this[type + 'SegEl'];
            var html = '';
            var renderedSegs = [];
            var i;

            if (segs.length) {

                // build a large concatenation of segment HTML
                for (i = 0; i < segs.length; i++) {
                    html += this.fillSegHtml(type, segs[i]);
                }

                // Grab individual elements from the combined HTML string. Use each as the default rendering.
                // Then, compute the 'el' for each segment.
                $(html).each(function (i, node) {
                    var seg = segs[i];
                    var el = $(node);

                    // allow custom filter methods per-type
                    if (segElMethod) {
                        el = segElMethod.call(_this, seg, el);
                    }

                    if (el) { // custom filters did not cancel the render
                        el = $(el); // allow custom filter to return raw DOM node

                        // correct element type? (would be bad if a non-TD were inserted into a table for example)
                        if (el.is(_this.fillSegTag)) {
                            seg.el = el;
                            renderedSegs.push(seg);
                        }
                    }
                });
            }

            return renderedSegs;
        },

        fillSegTag: 'div', // subclasses can override


        // Builds the HTML needed for one fill segment. Generic enought o work with different types.
        fillSegHtml: function (type, seg) {
            var classesMethod = this[type + 'SegClasses']; // custom hooks per-type
            var stylesMethod = this[type + 'SegStyles']; //
            var classes = classesMethod ? classesMethod.call(this, seg) : [];
            var styles = stylesMethod ? stylesMethod.call(this, seg) : ''; // a semi-colon separated CSS property string

            return '<' + this.fillSegTag +
                    (classes.length ? ' class="' + classes.join(' ') + '"' : '') +
                    (styles ? ' style="' + styles + '"' : '') +
                    ' />';
        },

        /* Generic rendering utilities for subclasses
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a day-of-week header row.
        // TODO: move to another class. not applicable to all Grids
        headHtml: function () {
            return '' +
                    '<div class="fc-row ' + this.view.widgetHeaderClass + '">' +
                    '<table>' +
                    '<thead>' +
                    this.rowHtml('head') + // leverages RowRenderer
                    '</thead>' +
                    '</table>' +
                    '</div>';
        },

        // Used by the `headHtml` method, via RowRenderer, for rendering the HTML of a day-of-week header cell
        // TODO: move to another class. not applicable to all Grids
        headCellHtml: function (cell) {
            var view = this.view;
            var date = cell.start;

            return '' +
                    '<th class="fc-day-header ' + view.widgetHeaderClass + ' fc-' + dayIDs[date.day()] + '">' +
                    htmlEscape(date.format(this.colHeadFormat)) +
                    '</th>';
        },

        // Renders the HTML for a single-day background cell
        bgCellHtml: function (cell) {
            var view = this.view;
            var date = cell.start;
            var classes = this.getDayClasses(date);

            classes.unshift('fc-day', view.widgetContentClass);

            return '<td class="' + classes.join(' ') + '"' +
                    ' data-date="' + date.format('YYYY-MM-DD') + '"' + // if date has a time, won't format it
                    '></td>';
        },

        // Computes HTML classNames for a single-day cell
        getDayClasses: function (date) {
            var view = this.view;
            var today = view.calendar.getNow().stripTime();
            var classes = ['fc-' + dayIDs[date.day()]];

            if (
                    view.name === 'month' &&
                    date.month() != view.intervalStart.month()
                    ) {
                classes.push('fc-other-month');
            }

            if (date.isSame(today, 'day')) {
                classes.push(
                        'fc-today',
                        view.highlightStateClass
                        );
            } else if (date < today) {
                classes.push('fc-past');
            } else {
                classes.push('fc-future');
            }

            return classes;
        }

    });

    /* Event-rendering and event-interaction methods for the abstract Grid class
     ----------------------------------------------------------------------------------------------------------------------*/

    Grid.mixin({

        mousedOverSeg: null, // the segment object the user's mouse is over. null if over nothing
        isDraggingSeg: false, // is a segment being dragged? boolean
        isResizingSeg: false, // is a segment being resized? boolean
        segs: null, // the event segments currently rendered in the grid


        // Renders the given events onto the grid
        renderEvents: function (events) {
            var segs = this.eventsToSegs(events);
            var bgSegs = [];
            var fgSegs = [];
            var i, seg;

            for (i = 0; i < segs.length; i++) {
                seg = segs[i];

                if (isBgEvent(seg.event)) {
                    bgSegs.push(seg);
                } else {
                    fgSegs.push(seg);
                }
            }

            // Render each different type of segment.
            // Each function may return a subset of the segs, segs that were actually rendered.
            bgSegs = this.renderBgSegs(bgSegs) || bgSegs;
            fgSegs = this.renderFgSegs(fgSegs) || fgSegs;

            this.segs = bgSegs.concat(fgSegs);
        },

        // Unrenders all events currently rendered on the grid
        destroyEvents: function () {
            this.triggerSegMouseout(); // trigger an eventMouseout if user's mouse is over an event

            this.destroyFgSegs();
            this.destroyBgSegs();

            this.segs = null;
        },

        // Retrieves all rendered segment objects currently rendered on the grid
        getEventSegs: function () {
            return this.segs || [];
        },

        /* Foreground Segment Rendering
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders foreground event segments onto the grid. May return a subset of segs that were rendered.
        renderFgSegs: function (segs) {
            // subclasses must implement
        },

        // Unrenders all currently rendered foreground segments
        destroyFgSegs: function () {
            // subclasses must implement
        },

        // Renders and assigns an `el` property for each foreground event segment.
        // Only returns segments that successfully rendered.
        // A utility that subclasses may use.
        renderFgSegEls: function (segs, disableResizing) {
            var view = this.view;
            var html = '';
            var renderedSegs = [];
            var i;

            if (segs.length) { // don't build an empty html string

                // build a large concatenation of event segment HTML
                for (i = 0; i < segs.length; i++) {
                    html += this.fgSegHtml(segs[i], disableResizing);
                }

                // Grab individual elements from the combined HTML string. Use each as the default rendering.
                // Then, compute the 'el' for each segment. An el might be null if the eventRender callback returned false.
                $(html).each(function (i, node) {
                    var seg = segs[i];
                    var el = view.resolveEventEl(seg.event, $(node));

                    if (el) {
                        el.data('fc-seg', seg); // used by handlers
                        seg.el = el;
                        renderedSegs.push(seg);
                    }
                });
            }

            return renderedSegs;
        },

        // Generates the HTML for the default rendering of a foreground event segment. Used by renderFgSegEls()
        fgSegHtml: function (seg, disableResizing) {
            // subclasses should implement
        },

        /* Background Segment Rendering
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders the given background event segments onto the grid.
        // Returns a subset of the segs that were actually rendered.
        renderBgSegs: function (segs) {
            return this.renderFill('bgEvent', segs);
        },

        // Unrenders all the currently rendered background event segments
        destroyBgSegs: function () {
            this.destroyFill('bgEvent');
        },

        // Renders a background event element, given the default rendering. Called by the fill system.
        bgEventSegEl: function (seg, el) {
            return this.view.resolveEventEl(seg.event, el); // will filter through eventRender
        },

        // Generates an array of classNames to be used for the default rendering of a background event.
        // Called by the fill system.
        bgEventSegClasses: function (seg) {
            var event = seg.event;
            var source = event.source || {};

            return ['fc-bgevent'].concat(
                    event.className,
                    source.className || []
                    );
        },

        // Generates a semicolon-separated CSS string to be used for the default rendering of a background event.
        // Called by the fill system.
        // TODO: consolidate with getEventSkinCss?
        bgEventSegStyles: function (seg) {
            var view = this.view;
            var event = seg.event;
            var source = event.source || {};
            var eventColor = event.color;
            var sourceColor = source.color;
            var optionColor = view.opt('eventColor');
            var backgroundColor =
                    event.backgroundColor ||
                    eventColor ||
                    source.backgroundColor ||
                    sourceColor ||
                    view.opt('eventBackgroundColor') ||
                    optionColor;

            if (backgroundColor) {
                return 'background-color:' + backgroundColor;
            }

            return '';
        },

        // Generates an array of classNames to be used for the rendering business hours overlay. Called by the fill system.
        businessHoursSegClasses: function (seg) {
            return ['fc-nonbusiness', 'fc-bgevent'];
        },

        /* Handlers
         ------------------------------------------------------------------------------------------------------------------*/


        // Attaches event-element-related handlers to the container element and leverage bubbling
        bindSegHandlers: function () {
            var _this = this;
            var view = this.view;

            $.each(
                    {
                        mouseenter: function (seg, ev) {
                            _this.triggerSegMouseover(seg, ev);
                        },
                        mouseleave: function (seg, ev) {
                            _this.triggerSegMouseout(seg, ev);
                        },
                        click: function (seg, ev) {
                            return view.trigger('eventClick', this, seg.event, ev); // can return `false` to cancel
                        },
                        mousedown: function (seg, ev) {
                            if ($(ev.target).is('.fc-resizer') && view.isEventResizable(seg.event)) {
                                _this.segResizeMousedown(seg, ev);
                            } else if (view.isEventDraggable(seg.event)) {
                                _this.segDragMousedown(seg, ev);
                            }
                        }
                    },
                    function (name, func) {
                        // attach the handler to the container element and only listen for real event elements via bubbling
                        _this.el.on(name, '.fc-event-container > *', function (ev) {
                            var seg = $(this).data('fc-seg'); // grab segment data. put there by View::renderEvents

                            // only call the handlers if there is not a drag/resize in progress
                            if (seg && !_this.isDraggingSeg && !_this.isResizingSeg) {
                                return func.call(this, seg, ev); // `this` will be the event element
                            }
                        });
                    }
            );
        },

        // Updates internal state and triggers handlers for when an event element is moused over
        triggerSegMouseover: function (seg, ev) {
            if (!this.mousedOverSeg) {
                this.mousedOverSeg = seg;
                this.view.trigger('eventMouseover', seg.el[0], seg.event, ev);
            }
        },

        // Updates internal state and triggers handlers for when an event element is moused out.
        // Can be given no arguments, in which case it will mouseout the segment that was previously moused over.
        triggerSegMouseout: function (seg, ev) {
            ev = ev || {}; // if given no args, make a mock mouse event

            if (this.mousedOverSeg) {
                seg = seg || this.mousedOverSeg; // if given no args, use the currently moused-over segment
                this.mousedOverSeg = null;
                this.view.trigger('eventMouseout', seg.el[0], seg.event, ev);
            }
        },

        /* Event Dragging
         ------------------------------------------------------------------------------------------------------------------*/


        // Called when the user does a mousedown on an event, which might lead to dragging.
        // Generic enough to work with any type of Grid.
        segDragMousedown: function (seg, ev) {
            var _this = this;
            var view = this.view;
            var el = seg.el;
            var event = seg.event;
            var dropLocation;

            // A clone of the original element that will move with the mouse
            var mouseFollower = new MouseFollower(seg.el, {
                parentEl: view.el,
                opacity: view.opt('dragOpacity'),
                revertDuration: view.opt('dragRevertDuration'),
                zIndex: 2 // one above the .fc-view
            });

            // Tracks mouse movement over the *view's* coordinate map. Allows dragging and dropping between subcomponents
            // of the view.
            var dragListener = new DragListener(view.coordMap, {
                distance: 5,
                scroll: view.opt('dragScroll'),
                listenStart: function (ev) {
                    mouseFollower.hide(); // don't show until we know this is a real drag
                    mouseFollower.start(ev);
                },
                dragStart: function (ev) {
                    _this.triggerSegMouseout(seg, ev); // ensure a mouseout on the manipulated event has been reported
                    _this.isDraggingSeg = true;
                    view.hideEvent(event); // hide all event segments. our mouseFollower will take over
                    view.trigger('eventDragStart', el[0], event, ev, {}); // last argument is jqui dummy
                },
                cellOver: function (cell, isOrig) {
                    var origCell = seg.cell || dragListener.origCell; // starting cell could be forced (DayGrid.limit)

                    dropLocation = _this.computeEventDrop(origCell, cell, event);
                    if (dropLocation) {
                        if (view.renderDrag(dropLocation, seg)) { // have the subclass render a visual indication
                            mouseFollower.hide(); // if the subclass is already using a mock event "helper", hide our own
                        } else {
                            mouseFollower.show();
                        }
                        if (isOrig) {
                            dropLocation = null; // needs to have moved cells to be a valid drop
                        }
                    } else {
                        // have the helper follow the mouse (no snapping) with a warning-style cursor
                        mouseFollower.show();
                        disableCursor();
                    }
                },
                cellOut: function () { // called before mouse moves to a different cell OR moved out of all cells
                    dropLocation = null;
                    view.destroyDrag(); // unrender whatever was done in renderDrag
                    mouseFollower.show(); // show in case we are moving out of all cells
                    enableCursor();
                },
                dragStop: function (ev) {
                    // do revert animation if hasn't changed. calls a callback when finished (whether animation or not)
                    mouseFollower.stop(!dropLocation, function () {
                        _this.isDraggingSeg = false;
                        view.destroyDrag();
                        view.showEvent(event);
                        view.trigger('eventDragStop', el[0], event, ev, {}); // last argument is jqui dummy

                        if (dropLocation) {
                            view.reportEventDrop(event, dropLocation, el, ev);
                        }
                    });
                    enableCursor();
                },
                listenStop: function () {
                    mouseFollower.stop(); // put in listenStop in case there was a mousedown but the drag never started
                }
            });

            dragListener.mousedown(ev); // start listening, which will eventually lead to a dragStart
        },

        // Given the cell an event drag began, and the cell event was dropped, calculates the new start/end/allDay
        // values for the event. Subclasses may override and set additional properties to be used by renderDrag.
        // A falsy returned value indicates an invalid drop.
        computeEventDrop: function (startCell, endCell, event) {
            var dragStart = startCell.start;
            var dragEnd = endCell.start;
            var delta;
            var newStart;
            var newEnd;
            var newAllDay;
            var dropLocation;

            if (dragStart.hasTime() === dragEnd.hasTime()) {
                delta = diffDayTime(dragEnd, dragStart);
                newStart = event.start.clone().add(delta);
                if (event.end === null) { // do we need to compute an end?
                    newEnd = null;
                } else {
                    newEnd = event.end.clone().add(delta);
                }
                newAllDay = event.allDay; // keep it the same
            } else {
                // if switching from day <-> timed, start should be reset to the dropped date, and the end cleared
                newStart = dragEnd.clone();
                newEnd = null; // end should be cleared
                newAllDay = !dragEnd.hasTime();
            }

            dropLocation = {
                start: newStart,
                end: newEnd,
                allDay: newAllDay
            };

            if (!this.view.calendar.isEventRangeAllowed(dropLocation, event)) {
                return null;
            }

            return dropLocation;
        },

        /* External Element Dragging
         ------------------------------------------------------------------------------------------------------------------*/


        // Called when a jQuery UI drag is initiated anywhere in the DOM
        documentDragStart: function (ev, ui) {
            var view = this.view;
            var el;
            var accept;

            if (view.opt('droppable')) { // only listen if this setting is on
                el = $(ev.target);

                // Test that the dragged element passes the dropAccept selector or filter function.
                // FYI, the default is "*" (matches all)
                accept = view.opt('dropAccept');
                if ($.isFunction(accept) ? accept.call(el[0], el) : el.is(accept)) {

                    this.startExternalDrag(el, ev, ui);
                }
            }
        },

        // Called when a jQuery UI drag starts and it needs to be monitored for cell dropping
        startExternalDrag: function (el, ev, ui) {
            var _this = this;
            var meta = getDraggedElMeta(el); // extra data about event drop, including possible event to create
            var dragListener;
            var dropLocation; // a null value signals an unsuccessful drag

            // listener that tracks mouse movement over date-associated pixel regions
            dragListener = new DragListener(this.coordMap, {
                cellOver: function (cell) {
                    dropLocation = _this.computeExternalDrop(cell, meta);
                    if (dropLocation) {
                        _this.renderDrag(dropLocation); // called without a seg parameter
                    } else { // invalid drop cell
                        disableCursor();
                    }
                },
                cellOut: function () {
                    dropLocation = null; // signal unsuccessful
                    _this.destroyDrag();
                    enableCursor();
                }
            });

            // gets called, only once, when jqui drag is finished
            $(document).one('dragstop', function (ev, ui) {
                _this.destroyDrag();
                enableCursor();

                if (dropLocation) { // element was dropped on a valid date/time cell
                    _this.view.reportExternalDrop(meta, dropLocation, el, ev, ui);
                }
            });

            dragListener.startDrag(ev); // start listening immediately
        },

        // Given a cell to be dropped upon, and misc data associated with the jqui drag (guaranteed to be a plain object),
        // returns start/end dates for the event that would result from the hypothetical drop. end might be null.
        // Returning a null value signals an invalid drop cell.
        computeExternalDrop: function (cell, meta) {
            var dropLocation = {
                start: cell.start.clone(),
                end: null
            };

            // if dropped on an all-day cell, and element's metadata specified a time, set it
            if (meta.startTime && !dropLocation.start.hasTime()) {
                dropLocation.start.time(meta.startTime);
            }

            if (meta.duration) {
                dropLocation.end = dropLocation.start.clone().add(meta.duration);
            }

            if (!this.view.calendar.isExternalDropRangeAllowed(dropLocation, meta.eventProps)) {
                return null;
            }

            return dropLocation;
        },

        /* Drag Rendering (for both events and an external elements)
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a visual indication of an event or external element being dragged.
        // `dropLocation` contains hypothetical start/end/allDay values the event would have if dropped. end can be null.
        // `seg` is the internal segment object that is being dragged. If dragging an external element, `seg` is null.
        // A truthy returned value indicates this method has rendered a helper element.
        renderDrag: function (dropLocation, seg) {
            // subclasses must implement
        },

        // Unrenders a visual indication of an event or external element being dragged
        destroyDrag: function () {
            // subclasses must implement
        },

        /* Resizing
         ------------------------------------------------------------------------------------------------------------------*/


        // Called when the user does a mousedown on an event's resizer, which might lead to resizing.
        // Generic enough to work with any type of Grid.
        segResizeMousedown: function (seg, ev) {
            var _this = this;
            var view = this.view;
            var calendar = view.calendar;
            var el = seg.el;
            var event = seg.event;
            var start = event.start;
            var oldEnd = calendar.getEventEnd(event);
            var newEnd; // falsy if invalid resize
            var dragListener;

            function destroy() { // resets the rendering to show the original event
                _this.destroyEventResize();
                view.showEvent(event);
                enableCursor();
            }

            // Tracks mouse movement over the *grid's* coordinate map
            dragListener = new DragListener(this.coordMap, {
                distance: 5,
                scroll: view.opt('dragScroll'),
                dragStart: function (ev) {
                    _this.triggerSegMouseout(seg, ev); // ensure a mouseout on the manipulated event has been reported
                    _this.isResizingSeg = true;
                    view.trigger('eventResizeStart', el[0], event, ev, {}); // last argument is jqui dummy
                },
                cellOver: function (cell) {
                    newEnd = cell.end;

                    if (!newEnd.isAfter(start)) { // was end moved before start?
                        newEnd = start.clone().add(// make the event span a single slot
                                diffDayTime(cell.end, cell.start) // assumes all slot durations are the same
                                );
                    }

                    if (newEnd.isSame(oldEnd)) {
                        newEnd = null;
                    } else if (!calendar.isEventRangeAllowed({start: start, end: newEnd}, event)) {
                        newEnd = null;
                        disableCursor();
                    } else {
                        _this.renderEventResize({start: start, end: newEnd}, seg);
                        view.hideEvent(event);
                    }
                },
                cellOut: function () { // called before mouse moves to a different cell OR moved out of all cells
                    newEnd = null;
                    destroy();
                },
                dragStop: function (ev) {
                    _this.isResizingSeg = false;
                    destroy();
                    view.trigger('eventResizeStop', el[0], event, ev, {}); // last argument is jqui dummy

                    if (newEnd) { // valid date to resize to?
                        view.reportEventResize(event, newEnd, el, ev);
                    }
                }
            });

            dragListener.mousedown(ev); // start listening, which will eventually lead to a dragStart
        },

        // Renders a visual indication of an event being resized.
        // `range` has the updated dates of the event. `seg` is the original segment object involved in the drag.
        renderEventResize: function (range, seg) {
            // subclasses must implement
        },

        // Unrenders a visual indication of an event being resized.
        destroyEventResize: function () {
            // subclasses must implement
        },

        /* Rendering Utils
         ------------------------------------------------------------------------------------------------------------------*/


        // Compute the text that should be displayed on an event's element.
        // `range` can be the Event object itself, or something range-like, with at least a `start`.
        // The `timeFormat` options and the grid's default format is used, but `formatStr` can override.
        getEventTimeText: function (range, formatStr) {

            formatStr = formatStr || this.eventTimeFormat;

            if (range.end && this.displayEventEnd) {
                return this.view.formatRange(range, formatStr);
            } else {
                return range.start.format(formatStr);
            }
        },

        // Generic utility for generating the HTML classNames for an event segment's element
        getSegClasses: function (seg, isDraggable, isResizable) {
            var event = seg.event;
            var classes = [
                'fc-event',
                seg.isStart ? 'fc-start' : 'fc-not-start',
                seg.isEnd ? 'fc-end' : 'fc-not-end'
            ].concat(
                    event.className,
                    event.source ? event.source.className : []
                    );

            if (isDraggable) {
                classes.push('fc-draggable');
            }
            if (isResizable) {
                classes.push('fc-resizable');
            }

            return classes;
        },

        // Utility for generating a CSS string with all the event skin-related properties
        getEventSkinCss: function (event) {
            var view = this.view;
            var source = event.source || {};
            var eventColor = event.color;
            var sourceColor = source.color;
            var optionColor = view.opt('eventColor');
            var backgroundColor =
                    event.backgroundColor ||
                    eventColor ||
                    source.backgroundColor ||
                    sourceColor ||
                    view.opt('eventBackgroundColor') ||
                    optionColor;
            var borderColor =
                    event.borderColor ||
                    eventColor ||
                    source.borderColor ||
                    sourceColor ||
                    view.opt('eventBorderColor') ||
                    optionColor;
            var textColor =
                    event.textColor ||
                    source.textColor ||
                    view.opt('eventTextColor');
            var statements = [];
            if (backgroundColor) {
                statements.push('background-color:' + backgroundColor);
            }
            if (borderColor) {
                statements.push('border-color:' + borderColor);
            }
            if (textColor) {
                statements.push('color:' + textColor);
            }
            return statements.join(';');
        },

        /* Converting events -> ranges -> segs
         ------------------------------------------------------------------------------------------------------------------*/


        // Converts an array of event objects into an array of event segment objects.
        // A custom `rangeToSegsFunc` may be given for arbitrarily slicing up events.
        eventsToSegs: function (events, rangeToSegsFunc) {
            var eventRanges = this.eventsToRanges(events);
            var segs = [];
            var i;

            for (i = 0; i < eventRanges.length; i++) {
                segs.push.apply(
                        segs,
                        this.eventRangeToSegs(eventRanges[i], rangeToSegsFunc)
                        );
            }

            return segs;
        },

        // Converts an array of events into an array of "range" objects.
        // A "range" object is a plain object with start/end properties denoting the time it covers. Also an event property.
        // For "normal" events, this will be identical to the event's start/end, but for "inverse-background" events,
        // will create an array of ranges that span the time *not* covered by the given event.
        eventsToRanges: function (events) {
            var _this = this;
            var eventsById = groupEventsById(events);
            var ranges = [];

            // group by ID so that related inverse-background events can be rendered together
            $.each(eventsById, function (id, eventGroup) {
                if (eventGroup.length) {
                    ranges.push.apply(
                            ranges,
                            isInverseBgEvent(eventGroup[0]) ?
                            _this.eventsToInverseRanges(eventGroup) :
                            _this.eventsToNormalRanges(eventGroup)
                            );
                }
            });

            return ranges;
        },

        // Converts an array of "normal" events (not inverted rendering) into a parallel array of ranges
        eventsToNormalRanges: function (events) {
            var calendar = this.view.calendar;
            var ranges = [];
            var i, event;
            var eventStart, eventEnd;

            for (i = 0; i < events.length; i++) {
                event = events[i];

                // make copies and normalize by stripping timezone
                eventStart = event.start.clone().stripZone();
                eventEnd = calendar.getEventEnd(event).stripZone();

                ranges.push({
                    event: event,
                    start: eventStart,
                    end: eventEnd,
                    eventStartMS: +eventStart,
                    eventDurationMS: eventEnd - eventStart
                });
            }

            return ranges;
        },

        // Converts an array of events, with inverse-background rendering, into an array of range objects.
        // The range objects will cover all the time NOT covered by the events.
        eventsToInverseRanges: function (events) {
            var view = this.view;
            var viewStart = view.start.clone().stripZone(); // normalize timezone
            var viewEnd = view.end.clone().stripZone(); // normalize timezone
            var normalRanges = this.eventsToNormalRanges(events); // will give us normalized dates we can use w/o copies
            var inverseRanges = [];
            var event0 = events[0]; // assign this to each range's `.event`
            var start = viewStart; // the end of the previous range. the start of the new range
            var i, normalRange;

            // ranges need to be in order. required for our date-walking algorithm
            normalRanges.sort(compareNormalRanges);

            for (i = 0; i < normalRanges.length; i++) {
                normalRange = normalRanges[i];

                // add the span of time before the event (if there is any)
                if (normalRange.start > start) { // compare millisecond time (skip any ambig logic)
                    inverseRanges.push({
                        event: event0,
                        start: start,
                        end: normalRange.start
                    });
                }

                start = normalRange.end;
            }

            // add the span of time after the last event (if there is any)
            if (start < viewEnd) { // compare millisecond time (skip any ambig logic)
                inverseRanges.push({
                    event: event0,
                    start: start,
                    end: viewEnd
                });
            }

            return inverseRanges;
        },

        // Slices the given event range into one or more segment objects.
        // A `rangeToSegsFunc` custom slicing function can be given.
        eventRangeToSegs: function (eventRange, rangeToSegsFunc) {
            var segs;
            var i, seg;

            if (rangeToSegsFunc) {
                segs = rangeToSegsFunc(eventRange);
            } else {
                segs = this.rangeToSegs(eventRange); // defined by the subclass
            }

            for (i = 0; i < segs.length; i++) {
                seg = segs[i];
                seg.event = eventRange.event;
                seg.eventStartMS = eventRange.eventStartMS;
                seg.eventDurationMS = eventRange.eventDurationMS;
            }

            return segs;
        }

    });


    /* Utilities
     ----------------------------------------------------------------------------------------------------------------------*/


    function isBgEvent(event) { // returns true if background OR inverse-background
        var rendering = getEventRendering(event);
        return rendering === 'background' || rendering === 'inverse-background';
    }


    function isInverseBgEvent(event) {
        return getEventRendering(event) === 'inverse-background';
    }


    function getEventRendering(event) {
        return firstDefined((event.source || {}).rendering, event.rendering);
    }


    function groupEventsById(events) {
        var eventsById = {};
        var i, event;

        for (i = 0; i < events.length; i++) {
            event = events[i];
            (eventsById[event._id] || (eventsById[event._id] = [])).push(event);
        }

        return eventsById;
    }


// A cmp function for determining which non-inverted "ranges" (see above) happen earlier
    function compareNormalRanges(range1, range2) {
        return range1.eventStartMS - range2.eventStartMS; // earlier ranges go first
    }


// A cmp function for determining which segments should take visual priority
// DOES NOT WORK ON INVERTED BACKGROUND EVENTS because they have no eventStartMS/eventDurationMS
    function compareSegs(seg1, seg2) {
        return seg1.eventStartMS - seg2.eventStartMS || // earlier events go first
                seg2.eventDurationMS - seg1.eventDurationMS || // tie? longer events go first
                seg2.event.allDay - seg1.event.allDay || // tie? put all-day events first (booleans cast to 0/1)
                (seg1.event.title || '').localeCompare(seg2.event.title); // tie? alphabetically by title
    }

    fc.compareSegs = compareSegs; // export


    /* External-Dragging-Element Data
     ----------------------------------------------------------------------------------------------------------------------*/

// Require all HTML5 data-* attributes used by FullCalendar to have this prefix.
// A value of '' will query attributes like data-event. A value of 'fc' will query attributes like data-fc-event.
    fc.dataAttrPrefix = '';

// Given a jQuery element that might represent a dragged FullCalendar event, returns an intermediate data structure
// to be used for Event Object creation.
// A defined `.eventProps`, even when empty, indicates that an event should be created.
    function getDraggedElMeta(el) {
        var prefix = fc.dataAttrPrefix;
        var eventProps; // properties for creating the event, not related to date/time
        var startTime; // a Duration
        var duration;
        var stick;

        if (prefix) {
            prefix += '-';
        }
        eventProps = el.data(prefix + 'event') || null;

        if (eventProps) {
            if (typeof eventProps === 'object') {
                eventProps = $.extend({}, eventProps); // make a copy
            } else { // something like 1 or true. still signal event creation
                eventProps = {};
            }

            // pluck special-cased date/time properties
            startTime = eventProps.start;
            if (startTime == null) {
                startTime = eventProps.time;
            } // accept 'time' as well
            duration = eventProps.duration;
            stick = eventProps.stick;
            delete eventProps.start;
            delete eventProps.time;
            delete eventProps.duration;
            delete eventProps.stick;
        }

        // fallback to standalone attribute values for each of the date/time properties
        if (startTime == null) {
            startTime = el.data(prefix + 'start');
        }
        if (startTime == null) {
            startTime = el.data(prefix + 'time');
        } // accept 'time' as well
        if (duration == null) {
            duration = el.data(prefix + 'duration');
        }
        if (stick == null) {
            stick = el.data(prefix + 'stick');
        }

        // massage into correct data types
        startTime = startTime != null ? moment.duration(startTime) : null;
        duration = duration != null ? moment.duration(duration) : null;
        stick = Boolean(stick);

        return {eventProps: eventProps, startTime: startTime, duration: duration, stick: stick};
    }


    /* A component that renders a grid of whole-days that runs horizontally. There can be multiple rows, one per week.
     ----------------------------------------------------------------------------------------------------------------------*/

    var DayGrid = Grid.extend({

        numbersVisible: false, // should render a row for day/week numbers? set by outside view. TODO: make internal
        bottomCoordPadding: 0, // hack for extending the hit area for the last row of the coordinate grid
        breakOnWeeks: null, // should create a new row for each week? set by outside view

        cellDates: null, // flat chronological array of each cell's dates
        dayToCellOffsets: null, // maps days offsets from grid's start date, to cell offsets

        rowEls: null, // set of fake row elements
        dayEls: null, // set of whole-day elements comprising the row's background
        helperEls: null, // set of cell skeleton elements for rendering the mock event "helper"


        // Renders the rows and columns into the component's `this.el`, which should already be assigned.
        // isRigid determins whether the individual rows should ignore the contents and be a constant height.
        // Relies on the view's colCnt and rowCnt. In the future, this component should probably be self-sufficient.
        render: function (isRigid) {
            var view = this.view;
            var rowCnt = this.rowCnt;
            var colCnt = this.colCnt;
            var cellCnt = rowCnt * colCnt;
            var html = '';
            var row;
            var i, cell;

            for (row = 0; row < rowCnt; row++) {
                html += this.dayRowHtml(row, isRigid);
            }
            this.el.html(html);

            this.rowEls = this.el.find('.fc-row');
            this.dayEls = this.el.find('.fc-day');

            // trigger dayRender with each cell's element
            for (i = 0; i < cellCnt; i++) {
                cell = this.getCell(i);
                view.trigger('dayRender', null, cell.start, this.dayEls.eq(i));
            }

            Grid.prototype.render.call(this); // call the super-method
        },

        destroy: function () {
            this.destroySegPopover();
            Grid.prototype.destroy.call(this); // call the super-method
        },

        // Generates the HTML for a single row. `row` is the row number.
        dayRowHtml: function (row, isRigid) {
            var view = this.view;
            var classes = ['fc-row', 'fc-week', view.widgetContentClass];

            if (isRigid) {
                classes.push('fc-rigid');
            }

            return '' +
                    '<div class="' + classes.join(' ') + '">' +
                    '<div class="fc-bg">' +
                    '<table>' +
                    this.rowHtml('day', row) + // leverages RowRenderer. calls dayCellHtml()
                    '</table>' +
                    '</div>' +
                    '<div class="fc-content-skeleton">' +
                    '<table>' +
                    (this.numbersVisible ?
                            '<thead>' +
                            this.rowHtml('number', row) + // leverages RowRenderer. View will define render method
                            '</thead>' :
                            ''
                            ) +
                    '</table>' +
                    '</div>' +
                    '</div>';
        },

        // Renders the HTML for a whole-day cell. Will eventually end up in the day-row's background.
        // We go through a 'day' row type instead of just doing a 'bg' row type so that the View can do custom rendering
        // specifically for whole-day rows, whereas a 'bg' might also be used for other purposes (TimeGrid bg for example).
        dayCellHtml: function (cell) {
            return this.bgCellHtml(cell);
        },

        /* Options
         ------------------------------------------------------------------------------------------------------------------*/


        // Computes a default column header formatting string if `colFormat` is not explicitly defined
        computeColHeadFormat: function () {
            if (this.rowCnt > 1) { // more than one week row. day numbers will be in each cell
                return 'ddd'; // "Sat"
            } else if (this.colCnt > 1) { // multiple days, so full single date string WON'T be in title text
                return this.view.opt('dayOfMonthFormat'); // "Sat 12/10"
            } else { // single day, so full single date string will probably be in title text
                return 'dddd'; // "Saturday"
            }
        },

        // Computes a default event time formatting string if `timeFormat` is not explicitly defined
        computeEventTimeFormat: function () {
            return this.view.opt('extraSmallTimeFormat'); // like "6p" or "6:30p"
        },

        // Computes a default `displayEventEnd` value if one is not expliclty defined
        computeDisplayEventEnd: function () {
            return this.colCnt == 1; // we'll likely have space if there's only one day
        },

        /* Cell System
         ------------------------------------------------------------------------------------------------------------------*/


        // Initializes row/col information
        updateCells: function () {
            var cellDates;
            var firstDay;
            var rowCnt;
            var colCnt;

            this.updateCellDates(); // populates cellDates and dayToCellOffsets
            cellDates = this.cellDates;

            if (this.breakOnWeeks) {
                // count columns until the day-of-week repeats
                firstDay = cellDates[0].day();
                for (colCnt = 1; colCnt < cellDates.length; colCnt++) {
                    if (cellDates[colCnt].day() == firstDay) {
                        break;
                    }
                }
                rowCnt = Math.ceil(cellDates.length / colCnt);
            } else {
                rowCnt = 1;
                colCnt = cellDates.length;
            }

            this.rowCnt = rowCnt;
            this.colCnt = colCnt;
        },

        // Populates cellDates and dayToCellOffsets
        updateCellDates: function () {
            var view = this.view;
            var date = this.start.clone();
            var dates = [];
            var offset = -1;
            var offsets = [];

            while (date.isBefore(this.end)) { // loop each day from start to end
                if (view.isHiddenDay(date)) {
                    offsets.push(offset + 0.5); // mark that it's between offsets
                } else {
                    offset++;
                    offsets.push(offset);
                    dates.push(date.clone());
                }
                date.add(1, 'days');
            }

            this.cellDates = dates;
            this.dayToCellOffsets = offsets;
        },

        // Given a cell object, generates a range object
        computeCellRange: function (cell) {
            var colCnt = this.colCnt;
            var index = cell.row * colCnt + (this.isRTL ? colCnt - cell.col - 1 : cell.col);
            var start = this.cellDates[index].clone();
            var end = start.clone().add(1, 'day');

            return {start: start, end: end};
        },

        // Retrieves the element representing the given row
        getRowEl: function (row) {
            return this.rowEls.eq(row);
        },

        // Retrieves the element representing the given column
        getColEl: function (col) {
            return this.dayEls.eq(col);
        },

        // Gets the whole-day element associated with the cell
        getCellDayEl: function (cell) {
            return this.dayEls.eq(cell.row * this.colCnt + cell.col);
        },

        // Overrides Grid's method for when row coordinates are computed
        computeRowCoords: function () {
            var rowCoords = Grid.prototype.computeRowCoords.call(this); // call the super-method

            // hack for extending last row (used by AgendaView)
            rowCoords[rowCoords.length - 1].bottom += this.bottomCoordPadding;

            return rowCoords;
        },

        /* Dates
         ------------------------------------------------------------------------------------------------------------------*/


        // Slices up a date range by row into an array of segments
        rangeToSegs: function (range) {
            var isRTL = this.isRTL;
            var rowCnt = this.rowCnt;
            var colCnt = this.colCnt;
            var segs = [];
            var first, last; // inclusive cell-offset range for given range
            var row;
            var rowFirst, rowLast; // inclusive cell-offset range for current row
            var isStart, isEnd;
            var segFirst, segLast; // inclusive cell-offset range for segment
            var seg;

            range = this.view.computeDayRange(range); // make whole-day range, considering nextDayThreshold
            first = this.dateToCellOffset(range.start);
            last = this.dateToCellOffset(range.end.subtract(1, 'days')); // offset of inclusive end date

            for (row = 0; row < rowCnt; row++) {
                rowFirst = row * colCnt;
                rowLast = rowFirst + colCnt - 1;

                // intersect segment's offset range with the row's
                segFirst = Math.max(rowFirst, first);
                segLast = Math.min(rowLast, last);

                // deal with in-between indices
                segFirst = Math.ceil(segFirst); // in-between starts round to next cell
                segLast = Math.floor(segLast); // in-between ends round to prev cell

                if (segFirst <= segLast) { // was there any intersection with the current row?

                    // must be matching integers to be the segment's start/end
                    isStart = segFirst === first;
                    isEnd = segLast === last;

                    // translate offsets to be relative to start-of-row
                    segFirst -= rowFirst;
                    segLast -= rowFirst;

                    seg = {row: row, isStart: isStart, isEnd: isEnd};
                    if (isRTL) {
                        seg.leftCol = colCnt - segLast - 1;
                        seg.rightCol = colCnt - segFirst - 1;
                    } else {
                        seg.leftCol = segFirst;
                        seg.rightCol = segLast;
                    }
                    segs.push(seg);
                }
            }

            return segs;
        },

        // Given a date, returns its chronolocial cell-offset from the first cell of the grid.
        // If the date lies between cells (because of hiddenDays), returns a floating-point value between offsets.
        // If before the first offset, returns a negative number.
        // If after the last offset, returns an offset past the last cell offset.
        // Only works for *start* dates of cells. Will not work for exclusive end dates for cells.
        dateToCellOffset: function (date) {
            var offsets = this.dayToCellOffsets;
            var day = date.diff(this.start, 'days');

            if (day < 0) {
                return offsets[0] - 1;
            } else if (day >= offsets.length) {
                return offsets[offsets.length - 1] + 1;
            } else {
                return offsets[day];
            }
        },

        /* Event Drag Visualization
         ------------------------------------------------------------------------------------------------------------------*/
        // TODO: move to DayGrid.event, similar to what we did with Grid's drag methods


        // Renders a visual indication of an event or external element being dragged.
        // The dropLocation's end can be null. seg can be null. See Grid::renderDrag for more info.
        renderDrag: function (dropLocation, seg) {
            var opacity;

            // always render a highlight underneath
            this.renderHighlight(
                    this.view.calendar.ensureVisibleEventRange(dropLocation) // needs to be a proper range
                    );

            // if a segment from the same calendar but another component is being dragged, render a helper event
            if (seg && !seg.el.closest(this.el).length) {

                this.renderRangeHelper(dropLocation, seg);

                opacity = this.view.opt('dragOpacity');
                if (opacity !== undefined) {
                    this.helperEls.css('opacity', opacity);
                }

                return true; // a helper has been rendered
            }
        },

        // Unrenders any visual indication of a hovering event
        destroyDrag: function () {
            this.destroyHighlight();
            this.destroyHelper();
        },

        /* Event Resize Visualization
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a visual indication of an event being resized
        renderEventResize: function (range, seg) {
            this.renderHighlight(range);
            this.renderRangeHelper(range, seg);
        },

        // Unrenders a visual indication of an event being resized
        destroyEventResize: function () {
            this.destroyHighlight();
            this.destroyHelper();
        },

        /* Event Helper
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a mock "helper" event. `sourceSeg` is the associated internal segment object. It can be null.
        renderHelper: function (event, sourceSeg) {
            var helperNodes = [];
            var segs = this.eventsToSegs([event]);
            var rowStructs;

            segs = this.renderFgSegEls(segs); // assigns each seg's el and returns a subset of segs that were rendered
            rowStructs = this.renderSegRows(segs);

            // inject each new event skeleton into each associated row
            this.rowEls.each(function (row, rowNode) {
                var rowEl = $(rowNode); // the .fc-row
                var skeletonEl = $('<div class="fc-helper-skeleton"><table/></div>'); // will be absolutely positioned
                var skeletonTop;

                // If there is an original segment, match the top position. Otherwise, put it at the row's top level
                if (sourceSeg && sourceSeg.row === row) {
                    skeletonTop = sourceSeg.el.position().top;
                } else {
                    skeletonTop = rowEl.find('.fc-content-skeleton tbody').position().top;
                }

                skeletonEl.css('top', skeletonTop)
                        .find('table')
                        .append(rowStructs[row].tbodyEl);

                rowEl.append(skeletonEl);
                helperNodes.push(skeletonEl[0]);
            });

            this.helperEls = $(helperNodes); // array -> jQuery set
        },

        // Unrenders any visual indication of a mock helper event
        destroyHelper: function () {
            if (this.helperEls) {
                this.helperEls.remove();
                this.helperEls = null;
            }
        },

        /* Fill System (highlight, background events, business hours)
         ------------------------------------------------------------------------------------------------------------------*/


        fillSegTag: 'td', // override the default tag name


        // Renders a set of rectangles over the given segments of days.
        // Only returns segments that successfully rendered.
        renderFill: function (type, segs) {
            var nodes = [];
            var i, seg;
            var skeletonEl;

            segs = this.renderFillSegEls(type, segs); // assignes `.el` to each seg. returns successfully rendered segs

            for (i = 0; i < segs.length; i++) {
                seg = segs[i];
                skeletonEl = this.renderFillRow(type, seg);
                this.rowEls.eq(seg.row).append(skeletonEl);
                nodes.push(skeletonEl[0]);
            }

            this.elsByFill[type] = $(nodes);

            return segs;
        },

        // Generates the HTML needed for one row of a fill. Requires the seg's el to be rendered.
        renderFillRow: function (type, seg) {
            var colCnt = this.colCnt;
            var startCol = seg.leftCol;
            var endCol = seg.rightCol + 1;
            var skeletonEl;
            var trEl;

            skeletonEl = $(
                    '<div class="fc-' + type.toLowerCase() + '-skeleton">' +
                    '<table><tr/></table>' +
                    '</div>'
                    );
            trEl = skeletonEl.find('tr');

            if (startCol > 0) {
                trEl.append('<td colspan="' + startCol + '"/>');
            }

            trEl.append(
                    seg.el.attr('colspan', endCol - startCol)
                    );

            if (endCol < colCnt) {
                trEl.append('<td colspan="' + (colCnt - endCol) + '"/>');
            }

            this.bookendCells(trEl, type);

            return skeletonEl;
        }

    });

    /* Event-rendering methods for the DayGrid class
     ----------------------------------------------------------------------------------------------------------------------*/

    DayGrid.mixin({

        rowStructs: null, // an array of objects, each holding information about a row's foreground event-rendering


        // Unrenders all events currently rendered on the grid
        destroyEvents: function () {
            this.destroySegPopover(); // removes the "more.." events popover
            Grid.prototype.destroyEvents.apply(this, arguments); // calls the super-method
        },

        // Retrieves all rendered segment objects currently rendered on the grid
        getEventSegs: function () {
            return Grid.prototype.getEventSegs.call(this) // get the segments from the super-method
                    .concat(this.popoverSegs || []); // append the segments from the "more..." popover
        },

        // Renders the given background event segments onto the grid
        renderBgSegs: function (segs) {

            // don't render timed background events
            var allDaySegs = $.grep(segs, function (seg) {
                return seg.event.allDay;
            });

            return Grid.prototype.renderBgSegs.call(this, allDaySegs); // call the super-method
        },

        // Renders the given foreground event segments onto the grid
        renderFgSegs: function (segs) {
            var rowStructs;

            // render an `.el` on each seg
            // returns a subset of the segs. segs that were actually rendered
            segs = this.renderFgSegEls(segs);

            rowStructs = this.rowStructs = this.renderSegRows(segs);

            // append to each row's content skeleton
            this.rowEls.each(function (i, rowNode) {
                $(rowNode).find('.fc-content-skeleton > table').append(
                        rowStructs[i].tbodyEl
                        );
            });

            return segs; // return only the segs that were actually rendered
        },

        // Unrenders all currently rendered foreground event segments
        destroyFgSegs: function () {
            var rowStructs = this.rowStructs || [];
            var rowStruct;

            while ((rowStruct = rowStructs.pop())) {
                rowStruct.tbodyEl.remove();
            }

            this.rowStructs = null;
        },

        // Uses the given events array to generate <tbody> elements that should be appended to each row's content skeleton.
        // Returns an array of rowStruct objects (see the bottom of `renderSegRow`).
        // PRECONDITION: each segment shoud already have a rendered and assigned `.el`
        renderSegRows: function (segs) {
            var rowStructs = [];
            var segRows;
            var row;

            segRows = this.groupSegRows(segs); // group into nested arrays

            // iterate each row of segment groupings
            for (row = 0; row < segRows.length; row++) {
                rowStructs.push(
                        this.renderSegRow(row, segRows[row])
                        );
            }

            return rowStructs;
        },

        // Builds the HTML to be used for the default element for an individual segment
        fgSegHtml: function (seg, disableResizing) {
            var view = this.view;
            var event = seg.event;
            var isDraggable = view.isEventDraggable(event);
            var isResizable = !disableResizing && event.allDay && seg.isEnd && view.isEventResizable(event);
            var classes = this.getSegClasses(seg, isDraggable, isResizable);
            var skinCss = this.getEventSkinCss(event);
            var timeHtml = '';
            var titleHtml;

            classes.unshift('fc-day-grid-event');

            // Only display a timed events time if it is the starting segment
            if (!event.allDay && seg.isStart) {
                timeHtml = '<span class="fc-time">' + htmlEscape(this.getEventTimeText(event)) + '</span>';
            }

            titleHtml =
                    '<span class="fc-title">' +
                    (htmlEscape(event.title || '') || '&nbsp;') + // we always want one line of height
                    '</span>';

            return '<a class="' + classes.join(' ') + '"' +
                    (event.url ?
                            ' href="' + htmlEscape(event.url) + '"' :
                            ''
                            ) +
                    (skinCss ?
                            ' style="' + skinCss + '"' :
                            ''
                            ) +
                    '>' +
                    '<div class="fc-content">' +
                    (this.isRTL ?
                            titleHtml + ' ' + timeHtml : // put a natural space in between
                            timeHtml + ' ' + titleHtml   //
                            ) +
                    '</div>' +
                    (isResizable ?
                            '<div class="fc-resizer"/>' :
                            ''
                            ) +
                    '</a>';
        },

        // Given a row # and an array of segments all in the same row, render a <tbody> element, a skeleton that contains
        // the segments. Returns object with a bunch of internal data about how the render was calculated.
        renderSegRow: function (row, rowSegs) {
            var colCnt = this.colCnt;
            var segLevels = this.buildSegLevels(rowSegs); // group into sub-arrays of levels
            var levelCnt = Math.max(1, segLevels.length); // ensure at least one level
            var tbody = $('<tbody/>');
            var segMatrix = []; // lookup for which segments are rendered into which level+col cells
            var cellMatrix = []; // lookup for all <td> elements of the level+col matrix
            var loneCellMatrix = []; // lookup for <td> elements that only take up a single column
            var i, levelSegs;
            var col;
            var tr;
            var j, seg;
            var td;

            // populates empty cells from the current column (`col`) to `endCol`
            function emptyCellsUntil(endCol) {
                while (col < endCol) {
                    // try to grab a cell from the level above and extend its rowspan. otherwise, create a fresh cell
                    td = (loneCellMatrix[i - 1] || [])[col];
                    if (td) {
                        td.attr(
                                'rowspan',
                                parseInt(td.attr('rowspan') || 1, 10) + 1
                                );
                    } else {
                        td = $('<td/>');
                        tr.append(td);
                    }
                    cellMatrix[i][col] = td;
                    loneCellMatrix[i][col] = td;
                    col++;
                }
            }

            for (i = 0; i < levelCnt; i++) { // iterate through all levels
                levelSegs = segLevels[i];
                col = 0;
                tr = $('<tr/>');

                segMatrix.push([]);
                cellMatrix.push([]);
                loneCellMatrix.push([]);

                // levelCnt might be 1 even though there are no actual levels. protect against this.
                // this single empty row is useful for styling.
                if (levelSegs) {
                    for (j = 0; j < levelSegs.length; j++) { // iterate through segments in level
                        seg = levelSegs[j];

                        emptyCellsUntil(seg.leftCol);

                        // create a container that occupies or more columns. append the event element.
                        td = $('<td class="fc-event-container"/>').append(seg.el);
                        if (seg.leftCol != seg.rightCol) {
                            td.attr('colspan', seg.rightCol - seg.leftCol + 1);
                        } else { // a single-column segment
                            loneCellMatrix[i][col] = td;
                        }

                        while (col <= seg.rightCol) {
                            cellMatrix[i][col] = td;
                            segMatrix[i][col] = seg;
                            col++;
                        }

                        tr.append(td);
                    }
                }

                emptyCellsUntil(colCnt); // finish off the row
                this.bookendCells(tr, 'eventSkeleton');
                tbody.append(tr);
            }

            return {// a "rowStruct"
                row: row, // the row number
                tbodyEl: tbody,
                cellMatrix: cellMatrix,
                segMatrix: segMatrix,
                segLevels: segLevels,
                segs: rowSegs
            };
        },

        // Stacks a flat array of segments, which are all assumed to be in the same row, into subarrays of vertical levels.
        buildSegLevels: function (segs) {
            var levels = [];
            var i, seg;
            var j;

            // Give preference to elements with certain criteria, so they have
            // a chance to be closer to the top.
            segs.sort(compareSegs);

            for (i = 0; i < segs.length; i++) {
                seg = segs[i];

                // loop through levels, starting with the topmost, until the segment doesn't collide with other segments
                for (j = 0; j < levels.length; j++) {
                    if (!isDaySegCollision(seg, levels[j])) {
                        break;
                    }
                }
                // `j` now holds the desired subrow index
                seg.level = j;

                // create new level array if needed and append segment
                (levels[j] || (levels[j] = [])).push(seg);
            }

            // order segments left-to-right. very important if calendar is RTL
            for (j = 0; j < levels.length; j++) {
                levels[j].sort(compareDaySegCols);
            }

            return levels;
        },

        // Given a flat array of segments, return an array of sub-arrays, grouped by each segment's row
        groupSegRows: function (segs) {
            var segRows = [];
            var i;

            for (i = 0; i < this.rowCnt; i++) {
                segRows.push([]);
            }

            for (i = 0; i < segs.length; i++) {
                segRows[segs[i].row].push(segs[i]);
            }

            return segRows;
        }

    });


// Computes whether two segments' columns collide. They are assumed to be in the same row.
    function isDaySegCollision(seg, otherSegs) {
        var i, otherSeg;

        for (i = 0; i < otherSegs.length; i++) {
            otherSeg = otherSegs[i];

            if (
                    otherSeg.leftCol <= seg.rightCol &&
                    otherSeg.rightCol >= seg.leftCol
                    ) {
                return true;
            }
        }

        return false;
    }


// A cmp function for determining the leftmost event
    function compareDaySegCols(a, b) {
        return a.leftCol - b.leftCol;
    }

    /* Methods relate to limiting the number events for a given day on a DayGrid
     ----------------------------------------------------------------------------------------------------------------------*/
// NOTE: all the segs being passed around in here are foreground segs

    DayGrid.mixin({

        segPopover: null, // the Popover that holds events that can't fit in a cell. null when not visible
        popoverSegs: null, // an array of segment objects that the segPopover holds. null when not visible


        destroySegPopover: function () {
            if (this.segPopover) {
                this.segPopover.hide(); // will trigger destruction of `segPopover` and `popoverSegs`
            }
        },

        // Limits the number of "levels" (vertically stacking layers of events) for each row of the grid.
        // `levelLimit` can be false (don't limit), a number, or true (should be computed).
        limitRows: function (levelLimit) {
            var rowStructs = this.rowStructs || [];
            var row; // row #
            var rowLevelLimit;

            for (row = 0; row < rowStructs.length; row++) {
                this.unlimitRow(row);

                if (!levelLimit) {
                    rowLevelLimit = false;
                } else if (typeof levelLimit === 'number') {
                    rowLevelLimit = levelLimit;
                } else {
                    rowLevelLimit = this.computeRowLevelLimit(row);
                }

                if (rowLevelLimit !== false) {
                    this.limitRow(row, rowLevelLimit);
                }
            }
        },

        // Computes the number of levels a row will accomodate without going outside its bounds.
        // Assumes the row is "rigid" (maintains a constant height regardless of what is inside).
        // `row` is the row number.
        computeRowLevelLimit: function (row) {
            var rowEl = this.rowEls.eq(row); // the containing "fake" row div
            var rowHeight = rowEl.height(); // TODO: cache somehow?
            var trEls = this.rowStructs[row].tbodyEl.children();
            var i, trEl;

            // Reveal one level <tr> at a time and stop when we find one out of bounds
            for (i = 0; i < trEls.length; i++) {
                trEl = trEls.eq(i).removeClass('fc-limited'); // get and reveal
                if (trEl.position().top + trEl.outerHeight() > rowHeight) {
                    return i;
                }
            }

            return false; // should not limit at all
        },

        // Limits the given grid row to the maximum number of levels and injects "more" links if necessary.
        // `row` is the row number.
        // `levelLimit` is a number for the maximum (inclusive) number of levels allowed.
        limitRow: function (row, levelLimit) {
            var _this = this;
            var rowStruct = this.rowStructs[row];
            var moreNodes = []; // array of "more" <a> links and <td> DOM nodes
            var col = 0; // col #, left-to-right (not chronologically)
            var cell;
            var levelSegs; // array of segment objects in the last allowable level, ordered left-to-right
            var cellMatrix; // a matrix (by level, then column) of all <td> jQuery elements in the row
            var limitedNodes; // array of temporarily hidden level <tr> and segment <td> DOM nodes
            var i, seg;
            var segsBelow; // array of segment objects below `seg` in the current `col`
            var totalSegsBelow; // total number of segments below `seg` in any of the columns `seg` occupies
            var colSegsBelow; // array of segment arrays, below seg, one for each column (offset from segs's first column)
            var td, rowspan;
            var segMoreNodes; // array of "more" <td> cells that will stand-in for the current seg's cell
            var j;
            var moreTd, moreWrap, moreLink;

            // Iterates through empty level cells and places "more" links inside if need be
            function emptyCellsUntil(endCol) { // goes from current `col` to `endCol`
                while (col < endCol) {
                    cell = _this.getCell(row, col);
                    segsBelow = _this.getCellSegs(cell, levelLimit);
                    if (segsBelow.length) {
                        td = cellMatrix[levelLimit - 1][col];
                        moreLink = _this.renderMoreLink(cell, segsBelow);
                        moreWrap = $('<div/>').append(moreLink);
                        td.append(moreWrap);
                        moreNodes.push(moreWrap[0]);
                    }
                    col++;
                }
            }

            if (levelLimit && levelLimit < rowStruct.segLevels.length) { // is it actually over the limit?
                levelSegs = rowStruct.segLevels[levelLimit - 1];
                cellMatrix = rowStruct.cellMatrix;

                limitedNodes = rowStruct.tbodyEl.children().slice(levelLimit) // get level <tr> elements past the limit
                        .addClass('fc-limited').get(); // hide elements and get a simple DOM-nodes array

                // iterate though segments in the last allowable level
                for (i = 0; i < levelSegs.length; i++) {
                    seg = levelSegs[i];
                    emptyCellsUntil(seg.leftCol); // process empty cells before the segment

                    // determine *all* segments below `seg` that occupy the same columns
                    colSegsBelow = [];
                    totalSegsBelow = 0;
                    while (col <= seg.rightCol) {
                        cell = this.getCell(row, col);
                        segsBelow = this.getCellSegs(cell, levelLimit);
                        colSegsBelow.push(segsBelow);
                        totalSegsBelow += segsBelow.length;
                        col++;
                    }

                    if (totalSegsBelow) { // do we need to replace this segment with one or many "more" links?
                        td = cellMatrix[levelLimit - 1][seg.leftCol]; // the segment's parent cell
                        rowspan = td.attr('rowspan') || 1;
                        segMoreNodes = [];

                        // make a replacement <td> for each column the segment occupies. will be one for each colspan
                        for (j = 0; j < colSegsBelow.length; j++) {
                            moreTd = $('<td class="fc-more-cell"/>').attr('rowspan', rowspan);
                            segsBelow = colSegsBelow[j];
                            cell = this.getCell(row, seg.leftCol + j);
                            moreLink = this.renderMoreLink(cell, [seg].concat(segsBelow)); // count seg as hidden too
                            moreWrap = $('<div/>').append(moreLink);
                            moreTd.append(moreWrap);
                            segMoreNodes.push(moreTd[0]);
                            moreNodes.push(moreTd[0]);
                        }

                        td.addClass('fc-limited').after($(segMoreNodes)); // hide original <td> and inject replacements
                        limitedNodes.push(td[0]);
                    }
                }

                emptyCellsUntil(this.colCnt); // finish off the level
                rowStruct.moreEls = $(moreNodes); // for easy undoing later
                rowStruct.limitedEls = $(limitedNodes); // for easy undoing later
            }
        },

        // Reveals all levels and removes all "more"-related elements for a grid's row.
        // `row` is a row number.
        unlimitRow: function (row) {
            var rowStruct = this.rowStructs[row];

            if (rowStruct.moreEls) {
                rowStruct.moreEls.remove();
                rowStruct.moreEls = null;
            }

            if (rowStruct.limitedEls) {
                rowStruct.limitedEls.removeClass('fc-limited');
                rowStruct.limitedEls = null;
            }
        },

        // Renders an <a> element that represents hidden event element for a cell.
        // Responsible for attaching click handler as well.
        renderMoreLink: function (cell, hiddenSegs) {
            var _this = this;
            var view = this.view;

            return $('<a class="fc-more"/>')
                    .text(
                            this.getMoreLinkText(hiddenSegs.length)
                            )
                    .on('click', function (ev) {
                        var clickOption = view.opt('eventLimitClick');
                        var date = cell.start;
                        var moreEl = $(this);
                        var dayEl = _this.getCellDayEl(cell);
                        var allSegs = _this.getCellSegs(cell);

                        // rescope the segments to be within the cell's date
                        var reslicedAllSegs = _this.resliceDaySegs(allSegs, date);
                        var reslicedHiddenSegs = _this.resliceDaySegs(hiddenSegs, date);

                        if (typeof clickOption === 'function') {
                            // the returned value can be an atomic option
                            clickOption = view.trigger('eventLimitClick', null, {
                                date: date,
                                dayEl: dayEl,
                                moreEl: moreEl,
                                segs: reslicedAllSegs,
                                hiddenSegs: reslicedHiddenSegs
                            }, ev);
                        }

                        if (clickOption === 'popover') {
                            _this.showSegPopover(cell, moreEl, reslicedAllSegs);
                        } else if (typeof clickOption === 'string') { // a view name
                            view.calendar.zoomTo(date, clickOption);
                        }
                    });
        },

        // Reveals the popover that displays all events within a cell
        showSegPopover: function (cell, moreLink, segs) {
            var _this = this;
            var view = this.view;
            var moreWrap = moreLink.parent(); // the <div> wrapper around the <a>
            var topEl; // the element we want to match the top coordinate of
            var options;

            if (this.rowCnt == 1) {
                topEl = view.el; // will cause the popover to cover any sort of header
            } else {
                topEl = this.rowEls.eq(cell.row); // will align with top of row
            }

            options = {
                className: 'fc-more-popover',
                content: this.renderSegPopoverContent(cell, segs),
                parentEl: this.el,
                top: topEl.offset().top,
                autoHide: true, // when the user clicks elsewhere, hide the popover
                viewportConstrain: view.opt('popoverViewportConstrain'),
                hide: function () {
                    // destroy everything when the popover is hidden
                    _this.segPopover.destroy();
                    _this.segPopover = null;
                    _this.popoverSegs = null;
                }
            };

            // Determine horizontal coordinate.
            // We use the moreWrap instead of the <td> to avoid border confusion.
            if (this.isRTL) {
                options.right = moreWrap.offset().left + moreWrap.outerWidth() + 1; // +1 to be over cell border
            } else {
                options.left = moreWrap.offset().left - 1; // -1 to be over cell border
            }

            this.segPopover = new Popover(options);
            this.segPopover.show();
        },

        // Builds the inner DOM contents of the segment popover
        renderSegPopoverContent: function (cell, segs) {
            var view = this.view;
            var isTheme = view.opt('theme');
            var title = cell.start.format(view.opt('dayPopoverFormat'));
            var content = $(
                    '<div class="fc-header ' + view.widgetHeaderClass + '">' +
                    '<span class="fc-close ' +
                    (isTheme ? 'ui-icon ui-icon-closethick' : 'fc-icon fc-icon-x') +
                    '"></span>' +
                    '<span class="fc-title">' +
                    htmlEscape(title) +
                    '</span>' +
                    '<div class="fc-clear"/>' +
                    '</div>' +
                    '<div class="fc-body ' + view.widgetContentClass + '">' +
                    '<div class="fc-event-container"></div>' +
                    '</div>'
                    );
            var segContainer = content.find('.fc-event-container');
            var i;

            // render each seg's `el` and only return the visible segs
            segs = this.renderFgSegEls(segs, true); // disableResizing=true
            this.popoverSegs = segs;

            for (i = 0; i < segs.length; i++) {

                // because segments in the popover are not part of a grid coordinate system, provide a hint to any
                // grids that want to do drag-n-drop about which cell it came from
                segs[i].cell = cell;

                segContainer.append(segs[i].el);
            }

            return content;
        },

        // Given the events within an array of segment objects, reslice them to be in a single day
        resliceDaySegs: function (segs, dayDate) {

            // build an array of the original events
            var events = $.map(segs, function (seg) {
                return seg.event;
            });

            var dayStart = dayDate.clone().stripTime();
            var dayEnd = dayStart.clone().add(1, 'days');
            var dayRange = {start: dayStart, end: dayEnd};

            // slice the events with a custom slicing function
            return this.eventsToSegs(
                    events,
                    function (range) {
                        var seg = intersectionToSeg(range, dayRange); // undefind if no intersection
                        return seg ? [seg] : []; // must return an array of segments
                    }
            );
        },

        // Generates the text that should be inside a "more" link, given the number of events it represents
        getMoreLinkText: function (num) {
            var opt = this.view.opt('eventLimitText');

            if (typeof opt === 'function') {
                return opt(num);
            } else {
                return '+' + num + ' ' + opt;
            }
        },

        // Returns segments within a given cell.
        // If `startLevel` is specified, returns only events including and below that level. Otherwise returns all segs.
        getCellSegs: function (cell, startLevel) {
            var segMatrix = this.rowStructs[cell.row].segMatrix;
            var level = startLevel || 0;
            var segs = [];
            var seg;

            while (level < segMatrix.length) {
                seg = segMatrix[level][cell.col];
                if (seg) {
                    segs.push(seg);
                }
                level++;
            }

            return segs;
        }

    });

    /* A component that renders one or more columns of vertical time slots
     ----------------------------------------------------------------------------------------------------------------------*/

    var TimeGrid = Grid.extend({

        slotDuration: null, // duration of a "slot", a distinct time segment on given day, visualized by lines
        snapDuration: null, // granularity of time for dragging and selecting

        minTime: null, // Duration object that denotes the first visible time of any given day
        maxTime: null, // Duration object that denotes the exclusive visible end time of any given day

        axisFormat: null, // formatting string for times running along vertical axis

        dayEls: null, // cells elements in the day-row background
        slatEls: null, // elements running horizontally across all columns

        slatTops: null, // an array of top positions, relative to the container. last item holds bottom of last slot

        helperEl: null, // cell skeleton element for rendering the mock event "helper"

        businessHourSegs: null,

        constructor: function () {
            Grid.apply(this, arguments); // call the super-constructor
            this.processOptions();
        },

        // Renders the time grid into `this.el`, which should already be assigned.
        // Relies on the view's colCnt. In the future, this component should probably be self-sufficient.
        render: function () {
            this.el.html(this.renderHtml());
            this.dayEls = this.el.find('.fc-day');
            this.slatEls = this.el.find('.fc-slats tr');

            this.computeSlatTops();
            this.renderBusinessHours();
            Grid.prototype.render.call(this); // call the super-method
        },

        renderBusinessHours: function () {
            var events = this.view.calendar.getBusinessHoursEvents();
            this.businessHourSegs = this.renderFill('businessHours', this.eventsToSegs(events), 'bgevent');
        },

        // Renders the basic HTML skeleton for the grid
        renderHtml: function () {
            return '' +
                    '<div class="fc-bg">' +
                    '<table>' +
                    this.rowHtml('slotBg') + // leverages RowRenderer, which will call slotBgCellHtml
                    '</table>' +
                    '</div>' +
                    '<div class="fc-slats">' +
                    '<table>' +
                    this.slatRowHtml() +
                    '</table>' +
                    '</div>';
        },

        // Renders the HTML for a vertical background cell behind the slots.
        // This method is distinct from 'bg' because we wanted a new `rowType` so the View could customize the rendering.
        slotBgCellHtml: function (cell) {
            return this.bgCellHtml(cell);
        },

        // Generates the HTML for the horizontal "slats" that run width-wise. Has a time axis on a side. Depends on RTL.
        slatRowHtml: function () {
            var view = this.view;
            var isRTL = this.isRTL;
            var html = '';
            var slotNormal = this.slotDuration.asMinutes() % 15 === 0;
            var slotTime = moment.duration(+this.minTime); // wish there was .clone() for durations
            var slotDate; // will be on the view's first day, but we only care about its time
            var minutes;
            var axisHtml;

            // Calculate the time for each slot
            while (slotTime < this.maxTime) {
                slotDate = this.start.clone().time(slotTime); // will be in UTC but that's good. to avoid DST issues
                minutes = slotDate.minutes();

                axisHtml =
                        '<td class="fc-axis fc-time ' + view.widgetContentClass + '" ' + view.axisStyleAttr() + '>' +
                        ((!slotNormal || !minutes) ? // if irregular slot duration, or on the hour, then display the time
                                '<span>' + // for matchCellWidths
                                htmlEscape(slotDate.format(this.axisFormat)) +
                                '</span>' :
                                ''
                                ) +
                        '</td>';

                html +=
                        '<tr ' + (!minutes ? '' : 'class="fc-minor"') + '>' +
                        (!isRTL ? axisHtml : '') +
                        '<td class="' + view.widgetContentClass + '"/>' +
                        (isRTL ? axisHtml : '') +
                        "</tr>";

                slotTime.add(this.slotDuration);
            }

            return html;
        },

        /* Options
         ------------------------------------------------------------------------------------------------------------------*/


        // Parses various options into properties of this object
        processOptions: function () {
            var view = this.view;
            var slotDuration = view.opt('slotDuration');
            var snapDuration = view.opt('snapDuration');

            slotDuration = moment.duration(slotDuration);
            snapDuration = snapDuration ? moment.duration(snapDuration) : slotDuration;

            this.slotDuration = slotDuration;
            this.snapDuration = snapDuration;

            this.minTime = moment.duration(view.opt('minTime'));
            this.maxTime = moment.duration(view.opt('maxTime'));

            this.axisFormat = view.opt('axisFormat') || view.opt('smallTimeFormat');
        },

        // Computes a default column header formatting string if `colFormat` is not explicitly defined
        computeColHeadFormat: function () {
            if (this.colCnt > 1) { // multiple days, so full single date string WON'T be in title text
                return this.view.opt('dayOfMonthFormat'); // "Sat 12/10"
            } else { // single day, so full single date string will probably be in title text
                return 'dddd'; // "Saturday"
            }
        },

        // Computes a default event time formatting string if `timeFormat` is not explicitly defined
        computeEventTimeFormat: function () {
            return this.view.opt('noMeridiemTimeFormat'); // like "6:30" (no AM/PM)
        },

        // Computes a default `displayEventEnd` value if one is not expliclty defined
        computeDisplayEventEnd: function () {
            return true;
        },

        /* Cell System
         ------------------------------------------------------------------------------------------------------------------*/


        // Initializes row/col information
        updateCells: function () {
            var view = this.view;
            var colData = [];
            var date;

            date = this.start.clone();
            while (date.isBefore(this.end)) {
                colData.push({
                    day: date.clone()
                });
                date.add(1, 'day');
                date = view.skipHiddenDays(date);
            }

            if (this.isRTL) {
                colData.reverse();
            }

            this.colData = colData;
            this.colCnt = colData.length;
            this.rowCnt = Math.ceil((this.maxTime - this.minTime) / this.snapDuration); // # of vertical snaps
        },

        // Given a cell object, generates a range object
        computeCellRange: function (cell) {
            var time = this.computeSnapTime(cell.row);
            var start = this.view.calendar.rezoneDate(cell.day).time(time);
            var end = start.clone().add(this.snapDuration);

            return {start: start, end: end};
        },

        // Retrieves the element representing the given column
        getColEl: function (col) {
            return this.dayEls.eq(col);
        },

        /* Dates
         ------------------------------------------------------------------------------------------------------------------*/


        // Given a row number of the grid, representing a "snap", returns a time (Duration) from its start-of-day
        computeSnapTime: function (row) {
            return moment.duration(this.minTime + this.snapDuration * row);
        },

        // Slices up a date range by column into an array of segments
        rangeToSegs: function (range) {
            var colCnt = this.colCnt;
            var segs = [];
            var seg;
            var col;
            var colDate;
            var colRange;

            // normalize :(
            range = {
                start: range.start.clone().stripZone(),
                end: range.end.clone().stripZone()
            };

            for (col = 0; col < colCnt; col++) {
                colDate = this.colData[col].day; // will be ambig time/timezone
                colRange = {
                    start: colDate.clone().time(this.minTime),
                    end: colDate.clone().time(this.maxTime)
                };
                seg = intersectionToSeg(range, colRange); // both will be ambig timezone
                if (seg) {
                    seg.col = col;
                    segs.push(seg);
                }
            }

            return segs;
        },

        /* Coordinates
         ------------------------------------------------------------------------------------------------------------------*/


        // Called when there is a window resize/zoom and we need to recalculate coordinates for the grid
        resize: function () {
            this.computeSlatTops();
            this.updateSegVerticals();
        },

        // Computes the top/bottom coordinates of each "snap" rows
        computeRowCoords: function () {
            var originTop = this.el.offset().top;
            var items = [];
            var i;
            var item;

            for (i = 0; i < this.rowCnt; i++) {
                item = {
                    top: originTop + this.computeTimeTop(this.computeSnapTime(i))
                };
                if (i > 0) {
                    items[i - 1].bottom = item.top;
                }
                items.push(item);
            }
            item.bottom = item.top + this.computeTimeTop(this.computeSnapTime(i));

            return items;
        },

        // Computes the top coordinate, relative to the bounds of the grid, of the given date.
        // A `startOfDayDate` must be given for avoiding ambiguity over how to treat midnight.
        computeDateTop: function (date, startOfDayDate) {
            return this.computeTimeTop(
                    moment.duration(
                            date.clone().stripZone() - startOfDayDate.clone().stripTime()
                            )
                    );
        },

        // Computes the top coordinate, relative to the bounds of the grid, of the given time (a Duration).
        computeTimeTop: function (time) {
            var slatCoverage = (time - this.minTime) / this.slotDuration; // floating-point value of # of slots covered
            var slatIndex;
            var slatRemainder;
            var slatTop;
            var slatBottom;

            // constrain. because minTime/maxTime might be customized
            slatCoverage = Math.max(0, slatCoverage);
            slatCoverage = Math.min(this.slatEls.length, slatCoverage);

            slatIndex = Math.floor(slatCoverage); // an integer index of the furthest whole slot
            slatRemainder = slatCoverage - slatIndex;
            slatTop = this.slatTops[slatIndex]; // the top position of the furthest whole slot

            if (slatRemainder) { // time spans part-way into the slot
                slatBottom = this.slatTops[slatIndex + 1];
                return slatTop + (slatBottom - slatTop) * slatRemainder; // part-way between slots
            } else {
                return slatTop;
            }
        },

        // Queries each `slatEl` for its position relative to the grid's container and stores it in `slatTops`.
        // Includes the the bottom of the last slat as the last item in the array.
        computeSlatTops: function () {
            var tops = [];
            var top;

            this.slatEls.each(function (i, node) {
                top = $(node).position().top;
                tops.push(top);
            });

            tops.push(top + this.slatEls.last().outerHeight()); // bottom of the last slat

            this.slatTops = tops;
        },

        /* Event Drag Visualization
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a visual indication of an event being dragged over the specified date(s).
        // dropLocation's end might be null, as well as `seg`. See Grid::renderDrag for more info.
        // A returned value of `true` signals that a mock "helper" event has been rendered.
        renderDrag: function (dropLocation, seg) {
            var opacity;

            if (seg) { // if there is event information for this drag, render a helper event
                this.renderRangeHelper(dropLocation, seg);

                opacity = this.view.opt('dragOpacity');
                if (opacity !== undefined) {
                    this.helperEl.css('opacity', opacity);
                }

                return true; // signal that a helper has been rendered
            } else {
                // otherwise, just render a highlight
                this.renderHighlight(
                        this.view.calendar.ensureVisibleEventRange(dropLocation) // needs to be a proper range
                        );
            }
        },

        // Unrenders any visual indication of an event being dragged
        destroyDrag: function () {
            this.destroyHelper();
            this.destroyHighlight();
        },

        /* Event Resize Visualization
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a visual indication of an event being resized
        renderEventResize: function (range, seg) {
            this.renderRangeHelper(range, seg);
        },

        // Unrenders any visual indication of an event being resized
        destroyEventResize: function () {
            this.destroyHelper();
        },

        /* Event Helper
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a mock "helper" event. `sourceSeg` is the original segment object and might be null (an external drag)
        renderHelper: function (event, sourceSeg) {
            var segs = this.eventsToSegs([event]);
            var tableEl;
            var i, seg;
            var sourceEl;

            segs = this.renderFgSegEls(segs); // assigns each seg's el and returns a subset of segs that were rendered
            tableEl = this.renderSegTable(segs);

            // Try to make the segment that is in the same row as sourceSeg look the same
            for (i = 0; i < segs.length; i++) {
                seg = segs[i];
                if (sourceSeg && sourceSeg.col === seg.col) {
                    sourceEl = sourceSeg.el;
                    seg.el.css({
                        left: sourceEl.css('left'),
                        right: sourceEl.css('right'),
                        'margin-left': sourceEl.css('margin-left'),
                        'margin-right': sourceEl.css('margin-right')
                    });
                }
            }

            this.helperEl = $('<div class="fc-helper-skeleton"/>')
                    .append(tableEl)
                    .appendTo(this.el);
        },

        // Unrenders any mock helper event
        destroyHelper: function () {
            if (this.helperEl) {
                this.helperEl.remove();
                this.helperEl = null;
            }
        },

        /* Selection
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a visual indication of a selection. Overrides the default, which was to simply render a highlight.
        renderSelection: function (range) {
            if (this.view.opt('selectHelper')) { // this setting signals that a mock helper event should be rendered
                this.renderRangeHelper(range);
            } else {
                this.renderHighlight(range);
            }
        },

        // Unrenders any visual indication of a selection
        destroySelection: function () {
            this.destroyHelper();
            this.destroyHighlight();
        },

        /* Fill System (highlight, background events, business hours)
         ------------------------------------------------------------------------------------------------------------------*/


        // Renders a set of rectangles over the given time segments.
        // Only returns segments that successfully rendered.
        renderFill: function (type, segs, className) {
            var segCols;
            var skeletonEl;
            var trEl;
            var col, colSegs;
            var tdEl;
            var containerEl;
            var dayDate;
            var i, seg;

            if (segs.length) {

                segs = this.renderFillSegEls(type, segs); // assignes `.el` to each seg. returns successfully rendered segs
                segCols = this.groupSegCols(segs); // group into sub-arrays, and assigns 'col' to each seg

                className = className || type.toLowerCase();
                skeletonEl = $(
                        '<div class="fc-' + className + '-skeleton">' +
                        '<table><tr/></table>' +
                        '</div>'
                        );
                trEl = skeletonEl.find('tr');

                for (col = 0; col < segCols.length; col++) {
                    colSegs = segCols[col];
                    tdEl = $('<td/>').appendTo(trEl);

                    if (colSegs.length) {
                        containerEl = $('<div class="fc-' + className + '-container"/>').appendTo(tdEl);
                        dayDate = this.colData[col].day;

                        for (i = 0; i < colSegs.length; i++) {
                            seg = colSegs[i];
                            containerEl.append(
                                    seg.el.css({
                                        top: this.computeDateTop(seg.start, dayDate),
                                        bottom: -this.computeDateTop(seg.end, dayDate) // the y position of the bottom edge
                                    })
                                    );
                        }
                    }
                }

                this.bookendCells(trEl, type);

                this.el.append(skeletonEl);
                this.elsByFill[type] = skeletonEl;
            }

            return segs;
        }

    });

    /* Event-rendering methods for the TimeGrid class
     ----------------------------------------------------------------------------------------------------------------------*/

    TimeGrid.mixin({

        eventSkeletonEl: null, // has cells with event-containers, which contain absolutely positioned event elements


        // Renders the given foreground event segments onto the grid
        renderFgSegs: function (segs) {
            segs = this.renderFgSegEls(segs); // returns a subset of the segs. segs that were actually rendered

            this.el.append(
                    this.eventSkeletonEl = $('<div class="fc-content-skeleton"/>')
                    .append(this.renderSegTable(segs))
                    );

            return segs; // return only the segs that were actually rendered
        },

        // Unrenders all currently rendered foreground event segments
        destroyFgSegs: function (segs) {
            if (this.eventSkeletonEl) {
                this.eventSkeletonEl.remove();
                this.eventSkeletonEl = null;
            }
        },

        // Renders and returns the <table> portion of the event-skeleton.
        // Returns an object with properties 'tbodyEl' and 'segs'.
        renderSegTable: function (segs) {
            var tableEl = $('<table><tr/></table>');
            var trEl = tableEl.find('tr');
            var segCols;
            var i, seg;
            var col, colSegs;
            var containerEl;

            segCols = this.groupSegCols(segs); // group into sub-arrays, and assigns 'col' to each seg

            this.computeSegVerticals(segs); // compute and assign top/bottom

            for (col = 0; col < segCols.length; col++) { // iterate each column grouping
                colSegs = segCols[col];
                placeSlotSegs(colSegs); // compute horizontal coordinates, z-index's, and reorder the array

                containerEl = $('<div class="fc-event-container"/>');

                // assign positioning CSS and insert into container
                for (i = 0; i < colSegs.length; i++) {
                    seg = colSegs[i];
                    seg.el.css(this.generateSegPositionCss(seg));

                    // if the height is short, add a className for alternate styling
                    if (seg.bottom - seg.top < 30) {
                        seg.el.addClass('fc-short');
                    }

                    containerEl.append(seg.el);
                }

                trEl.append($('<td/>').append(containerEl));
            }

            this.bookendCells(trEl, 'eventSkeleton');

            return tableEl;
        },

        // Refreshes the CSS top/bottom coordinates for each segment element. Probably after a window resize/zoom.
        // Repositions business hours segs too, so not just for events. Maybe shouldn't be here.
        updateSegVerticals: function () {
            var allSegs = (this.segs || []).concat(this.businessHourSegs || []);
            var i;

            this.computeSegVerticals(allSegs);

            for (i = 0; i < allSegs.length; i++) {
                allSegs[i].el.css(
                        this.generateSegVerticalCss(allSegs[i])
                        );
            }
        },

        // For each segment in an array, computes and assigns its top and bottom properties
        computeSegVerticals: function (segs) {
            var i, seg;

            for (i = 0; i < segs.length; i++) {
                seg = segs[i];
                seg.top = this.computeDateTop(seg.start, seg.start);
                seg.bottom = this.computeDateTop(seg.end, seg.start);
            }
        },

        // Renders the HTML for a single event segment's default rendering
        fgSegHtml: function (seg, disableResizing) {
            var view = this.view;
            var event = seg.event;
            var isDraggable = view.isEventDraggable(event);
            var isResizable = !disableResizing && seg.isEnd && view.isEventResizable(event);
            var classes = this.getSegClasses(seg, isDraggable, isResizable);
            var skinCss = this.getEventSkinCss(event);
            var timeText;
            var fullTimeText; // more verbose time text. for the print stylesheet
            var startTimeText; // just the start time text

            classes.unshift('fc-time-grid-event');

            if (view.isMultiDayEvent(event)) { // if the event appears to span more than one day...
                // Don't display time text on segments that run entirely through a day.
                // That would appear as midnight-midnight and would look dumb.
                // Otherwise, display the time text for the *segment's* times (like 6pm-midnight or midnight-10am)
                if (seg.isStart || seg.isEnd) {
                    timeText = this.getEventTimeText(seg);
                    fullTimeText = this.getEventTimeText(seg, 'LT');
                    startTimeText = this.getEventTimeText({start: seg.start});
                }
            } else {
                // Display the normal time text for the *event's* times
                timeText = this.getEventTimeText(event);
                fullTimeText = this.getEventTimeText(event, 'LT');
                startTimeText = this.getEventTimeText({start: event.start});
            }

            return '<a class="' + classes.join(' ') + '"' +
                    (event.url ?
                            ' href="' + htmlEscape(event.url) + '"' :
                            ''
                            ) +
                    (skinCss ?
                            ' style="' + skinCss + '"' :
                            ''
                            ) +
                    '>' +
                    '<div class="fc-content">' +
                    (timeText ?
                            '<div class="fc-time"' +
                            ' data-start="' + htmlEscape(startTimeText) + '"' +
                            ' data-full="' + htmlEscape(fullTimeText) + '"' +
                            '>' +
                            '<span>' + htmlEscape(timeText) + '</span>' +
                            '</div>' :
                            ''
                            ) +
                    (event.title ?
                            '<div class="fc-title">' +
                            htmlEscape(event.title) +
                            '</div>' :
                            ''
                            ) +
                    '</div>' +
                    '<div class="fc-bg"/>' +
                    (isResizable ?
                            '<div class="fc-resizer"/>' :
                            ''
                            ) +
                    '</a>';
        },

        // Generates an object with CSS properties/values that should be applied to an event segment element.
        // Contains important positioning-related properties that should be applied to any event element, customized or not.
        generateSegPositionCss: function (seg) {
            var shouldOverlap = this.view.opt('slotEventOverlap');
            var backwardCoord = seg.backwardCoord; // the left side if LTR. the right side if RTL. floating-point
            var forwardCoord = seg.forwardCoord; // the right side if LTR. the left side if RTL. floating-point
            var props = this.generateSegVerticalCss(seg); // get top/bottom first
            var left; // amount of space from left edge, a fraction of the total width
            var right; // amount of space from right edge, a fraction of the total width

            if (shouldOverlap) {
                // double the width, but don't go beyond the maximum forward coordinate (1.0)
                forwardCoord = Math.min(1, backwardCoord + (forwardCoord - backwardCoord) * 2);
            }

            if (this.isRTL) {
                left = 1 - forwardCoord;
                right = backwardCoord;
            } else {
                left = backwardCoord;
                right = 1 - forwardCoord;
            }

            props.zIndex = seg.level + 1; // convert from 0-base to 1-based
            props.left = left * 100 + '%';
            props.right = right * 100 + '%';

            if (shouldOverlap && seg.forwardPressure) {
                // add padding to the edge so that forward stacked events don't cover the resizer's icon
                props[this.isRTL ? 'marginLeft' : 'marginRight'] = 10 * 2; // 10 is a guesstimate of the icon's width
            }

            return props;
        },

        // Generates an object with CSS properties for the top/bottom coordinates of a segment element
        generateSegVerticalCss: function (seg) {
            return {
                top: seg.top,
                bottom: -seg.bottom // flipped because needs to be space beyond bottom edge of event container
            };
        },

        // Given a flat array of segments, return an array of sub-arrays, grouped by each segment's col
        groupSegCols: function (segs) {
            var segCols = [];
            var i;

            for (i = 0; i < this.colCnt; i++) {
                segCols.push([]);
            }

            for (i = 0; i < segs.length; i++) {
                segCols[segs[i].col].push(segs[i]);
            }

            return segCols;
        }

    });


// Given an array of segments that are all in the same column, sets the backwardCoord and forwardCoord on each.
// Also reorders the given array by date!
    function placeSlotSegs(segs) {
        var levels;
        var level0;
        var i;

        segs.sort(compareSegs); // order by date
        levels = buildSlotSegLevels(segs);
        computeForwardSlotSegs(levels);

        if ((level0 = levels[0])) {

            for (i = 0; i < level0.length; i++) {
                computeSlotSegPressures(level0[i]);
            }

            for (i = 0; i < level0.length; i++) {
                computeSlotSegCoords(level0[i], 0, 0);
            }
        }
    }


// Builds an array of segments "levels". The first level will be the leftmost tier of segments if the calendar is
// left-to-right, or the rightmost if the calendar is right-to-left. Assumes the segments are already ordered by date.
    function buildSlotSegLevels(segs) {
        var levels = [];
        var i, seg;
        var j;

        for (i = 0; i < segs.length; i++) {
            seg = segs[i];

            // go through all the levels and stop on the first level where there are no collisions
            for (j = 0; j < levels.length; j++) {
                if (!computeSlotSegCollisions(seg, levels[j]).length) {
                    break;
                }
            }

            seg.level = j;

            (levels[j] || (levels[j] = [])).push(seg);
        }

        return levels;
    }


// For every segment, figure out the other segments that are in subsequent
// levels that also occupy the same vertical space. Accumulate in seg.forwardSegs
    function computeForwardSlotSegs(levels) {
        var i, level;
        var j, seg;
        var k;

        for (i = 0; i < levels.length; i++) {
            level = levels[i];

            for (j = 0; j < level.length; j++) {
                seg = level[j];

                seg.forwardSegs = [];
                for (k = i + 1; k < levels.length; k++) {
                    computeSlotSegCollisions(seg, levels[k], seg.forwardSegs);
                }
            }
        }
    }


// Figure out which path forward (via seg.forwardSegs) results in the longest path until
// the furthest edge is reached. The number of segments in this path will be seg.forwardPressure
    function computeSlotSegPressures(seg) {
        var forwardSegs = seg.forwardSegs;
        var forwardPressure = 0;
        var i, forwardSeg;

        if (seg.forwardPressure === undefined) { // not already computed

            for (i = 0; i < forwardSegs.length; i++) {
                forwardSeg = forwardSegs[i];

                // figure out the child's maximum forward path
                computeSlotSegPressures(forwardSeg);

                // either use the existing maximum, or use the child's forward pressure
                // plus one (for the forwardSeg itself)
                forwardPressure = Math.max(
                        forwardPressure,
                        1 + forwardSeg.forwardPressure
                        );
            }

            seg.forwardPressure = forwardPressure;
        }
    }


// Calculate seg.forwardCoord and seg.backwardCoord for the segment, where both values range
// from 0 to 1. If the calendar is left-to-right, the seg.backwardCoord maps to "left" and
// seg.forwardCoord maps to "right" (via percentage). Vice-versa if the calendar is right-to-left.
//
// The segment might be part of a "series", which means consecutive segments with the same pressure
// who's width is unknown until an edge has been hit. `seriesBackwardPressure` is the number of
// segments behind this one in the current series, and `seriesBackwardCoord` is the starting
// coordinate of the first segment in the series.
    function computeSlotSegCoords(seg, seriesBackwardPressure, seriesBackwardCoord) {
        var forwardSegs = seg.forwardSegs;
        var i;

        if (seg.forwardCoord === undefined) { // not already computed

            if (!forwardSegs.length) {

                // if there are no forward segments, this segment should butt up against the edge
                seg.forwardCoord = 1;
            } else {

                // sort highest pressure first
                forwardSegs.sort(compareForwardSlotSegs);

                // this segment's forwardCoord will be calculated from the backwardCoord of the
                // highest-pressure forward segment.
                computeSlotSegCoords(forwardSegs[0], seriesBackwardPressure + 1, seriesBackwardCoord);
                seg.forwardCoord = forwardSegs[0].backwardCoord;
            }

            // calculate the backwardCoord from the forwardCoord. consider the series
            seg.backwardCoord = seg.forwardCoord -
                    (seg.forwardCoord - seriesBackwardCoord) / // available width for series
                    (seriesBackwardPressure + 1); // # of segments in the series

            // use this segment's coordinates to computed the coordinates of the less-pressurized
            // forward segments
            for (i = 0; i < forwardSegs.length; i++) {
                computeSlotSegCoords(forwardSegs[i], 0, seg.forwardCoord);
            }
        }
    }


// Find all the segments in `otherSegs` that vertically collide with `seg`.
// Append into an optionally-supplied `results` array and return.
    function computeSlotSegCollisions(seg, otherSegs, results) {
        results = results || [];

        for (var i = 0; i < otherSegs.length; i++) {
            if (isSlotSegCollision(seg, otherSegs[i])) {
                results.push(otherSegs[i]);
            }
        }

        return results;
    }


// Do these segments occupy the same vertical space?
    function isSlotSegCollision(seg1, seg2) {
        return seg1.bottom > seg2.top && seg1.top < seg2.bottom;
    }


// A cmp function for determining which forward segment to rely on more when computing coordinates.
    function compareForwardSlotSegs(seg1, seg2) {
        // put higher-pressure first
        return seg2.forwardPressure - seg1.forwardPressure ||
                // put segments that are closer to initial edge first (and favor ones with no coords yet)
                        (seg1.backwardCoord || 0) - (seg2.backwardCoord || 0) ||
                        // do normal sorting...
                        compareSegs(seg1, seg2);
            }

            /* An abstract class from which other views inherit from
             ----------------------------------------------------------------------------------------------------------------------*/

            var View = fc.View = Class.extend({

                type: null, // subclass' view name (string)
                name: null, // deprecated. use `type` instead

                calendar: null, // owner Calendar object
                options: null, // view-specific options
                coordMap: null, // a CoordMap object for converting pixel regions to dates
                el: null, // the view's containing element. set by Calendar

                // range the view is actually displaying (moments)
                start: null,
                end: null, // exclusive

                // range the view is formally responsible for (moments)
                // may be different from start/end. for example, a month view might have 1st-31st, excluding padded dates
                intervalStart: null,
                intervalEnd: null, // exclusive

                intervalDuration: null, // the whole-unit duration that is being displayed
                intervalUnit: null, // name of largest unit being displayed, like "month" or "week"

                isSelected: false, // boolean whether a range of time is user-selected or not

                // subclasses can optionally use a scroll container
                scrollerEl: null, // the element that will most likely scroll when content is too tall
                scrollTop: null, // cached vertical scroll value

                // classNames styled by jqui themes
                widgetHeaderClass: null,
                widgetContentClass: null,
                highlightStateClass: null,

                // for date utils, computed from options
                nextDayThreshold: null,
                isHiddenDayHash: null,

                // document handlers, bound to `this` object
                documentMousedownProxy: null, // TODO: doesn't work with touch


                constructor: function (calendar, viewOptions, viewType) {
                    this.calendar = calendar;
                    this.options = viewOptions;
                    this.type = this.name = viewType; // .name is deprecated

                    this.nextDayThreshold = moment.duration(this.opt('nextDayThreshold'));
                    this.initTheming();
                    this.initHiddenDays();

                    this.documentMousedownProxy = $.proxy(this, 'documentMousedown');

                    this.initialize();
                },

                // A good place for subclasses to initialize member variables
                initialize: function () {
                    // subclasses can implement
                },

                // Retrieves an option with the given name
                opt: function (name) {
                    var val;

                    val = this.options[name]; // look at view-specific options first
                    if (val !== undefined) {
                        return val;
                    }

                    val = this.calendar.options[name];
                    if ($.isPlainObject(val) && !isForcedAtomicOption(name)) { // view-option-hashes are deprecated
                        return smartProperty(val, this.type);
                    }

                    return val;
                },

                // Triggers handlers that are view-related. Modifies args before passing to calendar.
                trigger: function (name, thisObj) { // arguments beyond thisObj are passed along
                    var calendar = this.calendar;

                    return calendar.trigger.apply(
                            calendar,
                            [name, thisObj || this].concat(
                            Array.prototype.slice.call(arguments, 2), // arguments beyond thisObj
                            [this] // always make the last argument a reference to the view. TODO: deprecate
                            )
                            );
                },

                /* Dates
                 ------------------------------------------------------------------------------------------------------------------*/


                // Updates all internal dates to center around the given current date
                setDate: function (date) {
                    this.setRange(this.computeRange(date));
                },

                // Updates all internal dates for displaying the given range.
                // Expects all values to be normalized (like what computeRange does).
                setRange: function (range) {
                    $.extend(this, range);
                },

                // Given a single current date, produce information about what range to display.
                // Subclasses can override. Must return all properties.
                computeRange: function (date) {
                    var intervalDuration = moment.duration(this.opt('duration') || this.constructor.duration || {days: 1});
                    var intervalUnit = computeIntervalUnit(intervalDuration);
                    var intervalStart = date.clone().startOf(intervalUnit);
                    var intervalEnd = intervalStart.clone().add(intervalDuration);
                    var start, end;

                    // normalize the range's time-ambiguity
                    if (computeIntervalAs('days', intervalDuration)) { // whole-days?
                        intervalStart.stripTime();
                        intervalEnd.stripTime();
                    } else { // needs to have a time?
                        if (!intervalStart.hasTime()) {
                            intervalStart = this.calendar.rezoneDate(intervalStart); // convert to current timezone, with 00:00
                        }
                        if (!intervalEnd.hasTime()) {
                            intervalEnd = this.calendar.rezoneDate(intervalEnd); // convert to current timezone, with 00:00
                        }
                    }

                    start = intervalStart.clone();
                    start = this.skipHiddenDays(start);
                    end = intervalEnd.clone();
                    end = this.skipHiddenDays(end, -1, true); // exclusively move backwards

                    return {
                        intervalDuration: intervalDuration,
                        intervalUnit: intervalUnit,
                        intervalStart: intervalStart,
                        intervalEnd: intervalEnd,
                        start: start,
                        end: end
                    };
                },

                // Computes the new date when the user hits the prev button, given the current date
                computePrevDate: function (date) {
                    return this.skipHiddenDays(
                            date.clone().startOf(this.intervalUnit).subtract(this.intervalDuration), -1
                            );
                },

                // Computes the new date when the user hits the next button, given the current date
                computeNextDate: function (date) {
                    return this.skipHiddenDays(
                            date.clone().startOf(this.intervalUnit).add(this.intervalDuration)
                            );
                },

                /* Title and Date Formatting
                 ------------------------------------------------------------------------------------------------------------------*/


                // Computes what the title at the top of the calendar should be for this view
                computeTitle: function () {
                    return this.formatRange(
                            {start: this.intervalStart, end: this.intervalEnd},
                            this.opt('titleFormat') || this.computeTitleFormat(),
                            this.opt('titleRangeSeparator')
                            );
                },

                // Generates the format string that should be used to generate the title for the current date range.
                // Attempts to compute the most appropriate format if not explicitly specified with `titleFormat`.
                computeTitleFormat: function () {
                    if (this.intervalUnit == 'year') {
                        return 'YYYY';
                    } else if (this.intervalUnit == 'month') {
                        return this.opt('monthYearFormat'); // like "September 2014"
                    } else if (this.intervalDuration.as('days') > 1) {
                        return 'll'; // multi-day range. shorter, like "Sep 9 - 10 2014"
                    } else {
                        return 'LL'; // one day. longer, like "September 9 2014"
                    }
                },

                // Utility for formatting a range. Accepts a range object, formatting string, and optional separator.
                // Displays all-day ranges naturally, with an inclusive end. Takes the current isRTL into account.
                formatRange: function (range, formatStr, separator) {
                    var end = range.end;

                    if (!end.hasTime()) { // all-day?
                        end = end.clone().subtract(1); // convert to inclusive. last ms of previous day
                    }

                    return formatRange(range.start, end, formatStr, separator, this.opt('isRTL'));
                },

                /* Rendering
                 ------------------------------------------------------------------------------------------------------------------*/


                // Wraps the basic render() method with more View-specific logic. Called by the owner Calendar.
                renderView: function () {
                    this.render();
                    this.updateSize();
                    this.initializeScroll();
                    this.trigger('viewRender', this, this, this.el);

                    // attach handlers to document. do it here to allow for destroy/rerender
                    $(document).on('mousedown', this.documentMousedownProxy);
                },

                // Renders the view inside an already-defined `this.el`
                render: function () {
                    // subclasses should implement
                },

                // Wraps the basic destroy() method with more View-specific logic. Called by the owner Calendar.
                destroyView: function () {
                    this.unselect();
                    this.destroyViewEvents();
                    this.destroy();
                    this.trigger('viewDestroy', this, this, this.el);

                    $(document).off('mousedown', this.documentMousedownProxy);
                },

                // Clears the view's rendering
                destroy: function () {
                    this.el.empty(); // removes inner contents but leaves the element intact
                },

                // Initializes internal variables related to theming
                initTheming: function () {
                    var tm = this.opt('theme') ? 'ui' : 'fc';

                    this.widgetHeaderClass = tm + '-widget-header';
                    this.widgetContentClass = tm + '-widget-content';
                    this.highlightStateClass = tm + '-state-highlight';
                },

                /* Dimensions
                 ------------------------------------------------------------------------------------------------------------------*/


                // Refreshes anything dependant upon sizing of the container element of the grid
                updateSize: function (isResize) {
                    if (isResize) {
                        this.recordScroll();
                    }
                    this.updateHeight();
                    this.updateWidth();
                },

                // Refreshes the horizontal dimensions of the calendar
                updateWidth: function () {
                    // subclasses should implement
                },

                // Refreshes the vertical dimensions of the calendar
                updateHeight: function () {
                    var calendar = this.calendar; // we poll the calendar for height information

                    this.setHeight(
                            calendar.getSuggestedViewHeight(),
                            calendar.isHeightAuto()
                            );
                },

                // Updates the vertical dimensions of the calendar to the specified height.
                // if `isAuto` is set to true, height becomes merely a suggestion and the view should use its "natural" height.
                setHeight: function (height, isAuto) {
                    // subclasses should implement
                },

                /* Scroller
                 ------------------------------------------------------------------------------------------------------------------*/


                // Given the total height of the view, return the number of pixels that should be used for the scroller.
                // By default, uses this.scrollerEl, but can pass this in as well.
                // Utility for subclasses.
                computeScrollerHeight: function (totalHeight, scrollerEl) {
                    var both;
                    var otherHeight; // cumulative height of everything that is not the scrollerEl in the view (header+borders)

                    scrollerEl = scrollerEl || this.scrollerEl;
                    both = this.el.add(scrollerEl);

                    // fuckin IE8/9/10/11 sometimes returns 0 for dimensions. this weird hack was the only thing that worked
                    both.css({
                        position: 'relative', // cause a reflow, which will force fresh dimension recalculation
                        left: -1 // ensure reflow in case the el was already relative. negative is less likely to cause new scroll
                    });
                    otherHeight = this.el.outerHeight() - scrollerEl.height(); // grab the dimensions
                    both.css({position: '', left: ''}); // undo hack

                    return totalHeight - otherHeight;
                },

                // Sets the scroll value of the scroller to the initial pre-configured state prior to allowing the user to change it
                initializeScroll: function () {
                },

                // Called for remembering the current scroll value of the scroller.
                // Should be called before there is a destructive operation (like removing DOM elements) that might inadvertently
                // change the scroll of the container.
                recordScroll: function () {
                    if (this.scrollerEl) {
                        this.scrollTop = this.scrollerEl.scrollTop();
                    }
                },

                // Set the scroll value of the scroller to the previously recorded value.
                // Should be called after we know the view's dimensions have been restored following some type of destructive
                // operation (like temporarily removing DOM elements).
                restoreScroll: function () {
                    if (this.scrollTop !== null) {
                        this.scrollerEl.scrollTop(this.scrollTop);
                    }
                },

                /* Event Elements / Segments
                 ------------------------------------------------------------------------------------------------------------------*/


                // Wraps the basic renderEvents() method with more View-specific logic
                renderViewEvents: function (events) {
                    this.renderEvents(events);

                    this.eventSegEach(function (seg) {
                        this.trigger('eventAfterRender', seg.event, seg.event, seg.el);
                    });
                    this.trigger('eventAfterAllRender');
                },

                // Renders the events onto the view.
                renderEvents: function () {
                    // subclasses should implement
                },

                // Wraps the basic destroyEvents() method with more View-specific logic
                destroyViewEvents: function () {
                    this.eventSegEach(function (seg) {
                        this.trigger('eventDestroy', seg.event, seg.event, seg.el);
                    });

                    this.destroyEvents();
                },

                // Removes event elements from the view.
                destroyEvents: function () {
                    // subclasses should implement
                },

                // Given an event and the default element used for rendering, returns the element that should actually be used.
                // Basically runs events and elements through the eventRender hook.
                resolveEventEl: function (event, el) {
                    var custom = this.trigger('eventRender', event, event, el);

                    if (custom === false) { // means don't render at all
                        el = null;
                    } else if (custom && custom !== true) {
                        el = $(custom);
                    }

                    return el;
                },

                // Hides all rendered event segments linked to the given event
                showEvent: function (event) {
                    this.eventSegEach(function (seg) {
                        seg.el.css('visibility', '');
                    }, event);
                },

                // Shows all rendered event segments linked to the given event
                hideEvent: function (event) {
                    this.eventSegEach(function (seg) {
                        seg.el.css('visibility', 'hidden');
                    }, event);
                },

                // Iterates through event segments. Goes through all by default.
                // If the optional `event` argument is specified, only iterates through segments linked to that event.
                // The `this` value of the callback function will be the view.
                eventSegEach: function (func, event) {
                    var segs = this.getEventSegs();
                    var i;

                    for (i = 0; i < segs.length; i++) {
                        if (!event || segs[i].event._id === event._id) {
                            func.call(this, segs[i]);
                        }
                    }
                },

                // Retrieves all the rendered segment objects for the view
                getEventSegs: function () {
                    // subclasses must implement
                    return [];
                },

                /* Event Drag-n-Drop
                 ------------------------------------------------------------------------------------------------------------------*/


                // Computes if the given event is allowed to be dragged by the user
                isEventDraggable: function (event) {
                    var source = event.source || {};

                    return firstDefined(
                            event.startEditable,
                            source.startEditable,
                            this.opt('eventStartEditable'),
                            event.editable,
                            source.editable,
                            this.opt('editable')
                            );
                },

                // Must be called when an event in the view is dropped onto new location.
                // `dropLocation` is an object that contains the new start/end/allDay values for the event.
                reportEventDrop: function (event, dropLocation, el, ev) {
                    var calendar = this.calendar;
                    var mutateResult = calendar.mutateEvent(event, dropLocation);
                    var undoFunc = function () {
                        mutateResult.undo();
                        calendar.reportEventChange();
                    };

                    this.triggerEventDrop(event, mutateResult.dateDelta, undoFunc, el, ev);
                    calendar.reportEventChange(); // will rerender events
                },

                // Triggers event-drop handlers that have subscribed via the API
                triggerEventDrop: function (event, dateDelta, undoFunc, el, ev) {
                    this.trigger('eventDrop', el[0], event, dateDelta, undoFunc, ev, {}); // {} = jqui dummy
                },

                /* External Element Drag-n-Drop
                 ------------------------------------------------------------------------------------------------------------------*/


                // Must be called when an external element, via jQuery UI, has been dropped onto the calendar.
                // `meta` is the parsed data that has been embedded into the dragging event.
                // `dropLocation` is an object that contains the new start/end/allDay values for the event.
                reportExternalDrop: function (meta, dropLocation, el, ev, ui) {
                    var eventProps = meta.eventProps;
                    var eventInput;
                    var event;

                    // Try to build an event object and render it. TODO: decouple the two
                    if (eventProps) {
                        eventInput = $.extend({}, eventProps, dropLocation);
                        event = this.calendar.renderEvent(eventInput, meta.stick)[0]; // renderEvent returns an array
                    }

                    this.triggerExternalDrop(event, dropLocation, el, ev, ui);
                },

                // Triggers external-drop handlers that have subscribed via the API
                triggerExternalDrop: function (event, dropLocation, el, ev, ui) {

                    // trigger 'drop' regardless of whether element represents an event
                    this.trigger('drop', el[0], dropLocation.start, ev, ui);

                    if (event) {
                        this.trigger('eventReceive', null, event); // signal an external event landed
                    }
                },

                /* Drag-n-Drop Rendering (for both events and external elements)
                 ------------------------------------------------------------------------------------------------------------------*/


                // Renders a visual indication of a event or external-element drag over the given drop zone.
                // If an external-element, seg will be `null`
                renderDrag: function (dropLocation, seg) {
                    // subclasses must implement
                },

                // Unrenders a visual indication of an event or external-element being dragged.
                destroyDrag: function () {
                    // subclasses must implement
                },

                /* Event Resizing
                 ------------------------------------------------------------------------------------------------------------------*/


                // Computes if the given event is allowed to be resize by the user
                isEventResizable: function (event) {
                    var source = event.source || {};

                    return firstDefined(
                            event.durationEditable,
                            source.durationEditable,
                            this.opt('eventDurationEditable'),
                            event.editable,
                            source.editable,
                            this.opt('editable')
                            );
                },

                // Must be called when an event in the view has been resized to a new length
                reportEventResize: function (event, newEnd, el, ev) {
                    var calendar = this.calendar;
                    var mutateResult = calendar.mutateEvent(event, {end: newEnd});
                    var undoFunc = function () {
                        mutateResult.undo();
                        calendar.reportEventChange();
                    };

                    this.triggerEventResize(event, mutateResult.durationDelta, undoFunc, el, ev);
                    calendar.reportEventChange(); // will rerender events
                },

                // Triggers event-resize handlers that have subscribed via the API
                triggerEventResize: function (event, durationDelta, undoFunc, el, ev) {
                    this.trigger('eventResize', el[0], event, durationDelta, undoFunc, ev, {}); // {} = jqui dummy
                },

                /* Selection
                 ------------------------------------------------------------------------------------------------------------------*/


                // Selects a date range on the view. `start` and `end` are both Moments.
                // `ev` is the native mouse event that begin the interaction.
                select: function (range, ev) {
                    this.unselect(ev);
                    this.renderSelection(range);
                    this.reportSelection(range, ev);
                },

                // Renders a visual indication of the selection
                renderSelection: function (range) {
                    // subclasses should implement
                },

                // Called when a new selection is made. Updates internal state and triggers handlers.
                reportSelection: function (range, ev) {
                    this.isSelected = true;
                    this.trigger('select', null, range.start, range.end, ev);
                },

                // Undoes a selection. updates in the internal state and triggers handlers.
                // `ev` is the native mouse event that began the interaction.
                unselect: function (ev) {
                    if (this.isSelected) {
                        this.isSelected = false;
                        this.destroySelection();
                        this.trigger('unselect', null, ev);
                    }
                },

                // Unrenders a visual indication of selection
                destroySelection: function () {
                    // subclasses should implement
                },

                // Handler for unselecting when the user clicks something and the 'unselectAuto' setting is on
                documentMousedown: function (ev) {
                    var ignore;

                    // is there a selection, and has the user made a proper left click?
                    if (this.isSelected && this.opt('unselectAuto') && isPrimaryMouseButton(ev)) {

                        // only unselect if the clicked element is not identical to or inside of an 'unselectCancel' element
                        ignore = this.opt('unselectCancel');
                        if (!ignore || !$(ev.target).closest(ignore).length) {
                            this.unselect(ev);
                        }
                    }
                },

                /* Date Utils
                 ------------------------------------------------------------------------------------------------------------------*/


                // Initializes internal variables related to calculating hidden days-of-week
                initHiddenDays: function () {
                    var hiddenDays = this.opt('hiddenDays') || []; // array of day-of-week indices that are hidden
                    var isHiddenDayHash = []; // is the day-of-week hidden? (hash with day-of-week-index -> bool)
                    var dayCnt = 0;
                    var i;

                    if (this.opt('weekends') === false) {
                        hiddenDays.push(0, 6); // 0=sunday, 6=saturday
                    }

                    for (i = 0; i < 7; i++) {
                        if (
                                !(isHiddenDayHash[i] = $.inArray(i, hiddenDays) !== -1)
                                ) {
                            dayCnt++;
                        }
                    }

                    if (!dayCnt) {
                        throw 'invalid hiddenDays'; // all days were hidden? bad.
                    }

                    this.isHiddenDayHash = isHiddenDayHash;
                },

                // Is the current day hidden?
                // `day` is a day-of-week index (0-6), or a Moment
                isHiddenDay: function (day) {
                    if (moment.isMoment(day)) {
                        day = day.day();
                    }
                    return this.isHiddenDayHash[day];
                },

                // Incrementing the current day until it is no longer a hidden day, returning a copy.
                // If the initial value of `date` is not a hidden day, don't do anything.
                // Pass `isExclusive` as `true` if you are dealing with an end date.
                // `inc` defaults to `1` (increment one day forward each time)
                skipHiddenDays: function (date, inc, isExclusive) {
                    var out = date.clone();
                    inc = inc || 1;
                    while (
                            this.isHiddenDayHash[(out.day() + (isExclusive ? inc : 0) + 7) % 7]
                            ) {
                        out.add(inc, 'days');
                    }
                    return out;
                },

                // Returns the date range of the full days the given range visually appears to occupy.
                // Returns a new range object.
                computeDayRange: function (range) {
                    var startDay = range.start.clone().stripTime(); // the beginning of the day the range starts
                    var end = range.end;
                    var endDay = null;
                    var endTimeMS;

                    if (end) {
                        endDay = end.clone().stripTime(); // the beginning of the day the range exclusively ends
                        endTimeMS = +end.time(); // # of milliseconds into `endDay`

                        // If the end time is actually inclusively part of the next day and is equal to or
                        // beyond the next day threshold, adjust the end to be the exclusive end of `endDay`.
                        // Otherwise, leaving it as inclusive will cause it to exclude `endDay`.
                        if (endTimeMS && endTimeMS >= this.nextDayThreshold) {
                            endDay.add(1, 'days');
                        }
                    }

                    // If no end was specified, or if it is within `startDay` but not past nextDayThreshold,
                    // assign the default duration of one day.
                    if (!end || endDay <= startDay) {
                        endDay = startDay.clone().add(1, 'days');
                    }

                    return {start: startDay, end: endDay};
                },

                // Does the given event visually appear to occupy more than one day?
                isMultiDayEvent: function (event) {
                    var range = this.computeDayRange(event); // event is range-ish

                    return range.end.diff(range.start, 'days') > 1;
                }

            });

            function Calendar(element, instanceOptions) {
                var t = this;



                // Build options object
                // -----------------------------------------------------------------------------------
                // Precedence (lowest to highest): defaults, rtlDefaults, langOptions, instanceOptions

                instanceOptions = instanceOptions || {};

                var options = mergeOptions({}, defaults, instanceOptions);
                var langOptions;

                // determine language options
                if (options.lang in langOptionHash) {
                    langOptions = langOptionHash[options.lang];
                } else {
                    langOptions = langOptionHash[defaults.lang];
                }

                if (langOptions) { // if language options exist, rebuild...
                    options = mergeOptions({}, defaults, langOptions, instanceOptions);
                }

                if (options.isRTL) { // is isRTL, rebuild...
                    options = mergeOptions({}, defaults, rtlDefaults, langOptions || {}, instanceOptions);
                }



                // Exports
                // -----------------------------------------------------------------------------------

                t.options = options;
                t.render = render;
                t.destroy = destroy;
                t.refetchEvents = refetchEvents;
                t.reportEvents = reportEvents;
                t.reportEventChange = reportEventChange;
                t.rerenderEvents = renderEvents; // `renderEvents` serves as a rerender. an API method
                t.changeView = changeView;
                t.select = select;
                t.unselect = unselect;
                t.prev = prev;
                t.next = next;
                t.prevYear = prevYear;
                t.nextYear = nextYear;
                t.today = today;
                t.gotoDate = gotoDate;
                t.incrementDate = incrementDate;
                t.zoomTo = zoomTo;
                t.getDate = getDate;
                t.getCalendar = getCalendar;
                t.getView = getView;
                t.option = option;
                t.trigger = trigger;
                t.isValidViewType = isValidViewType;
                t.getViewButtonText = getViewButtonText;



                // Language-data Internals
                // -----------------------------------------------------------------------------------
                // Apply overrides to the current language's data


                var localeData = createObject(// make a cheap copy
                        getMomentLocaleData(options.lang) // will fall back to en
                        );

                if (options.monthNames) {
                    localeData._months = options.monthNames;
                }
                if (options.monthNamesShort) {
                    localeData._monthsShort = options.monthNamesShort;
                }
                if (options.dayNames) {
                    localeData._weekdays = options.dayNames;
                }
                if (options.dayNamesShort) {
                    localeData._weekdaysShort = options.dayNamesShort;
                }
                if (options.firstDay != null) {
                    var _week = createObject(localeData._week); // _week: { dow: # }
                    _week.dow = options.firstDay;
                    localeData._week = _week;
                }



                // Calendar-specific Date Utilities
                // -----------------------------------------------------------------------------------


                t.defaultAllDayEventDuration = moment.duration(options.defaultAllDayEventDuration);
                t.defaultTimedEventDuration = moment.duration(options.defaultTimedEventDuration);


                // Builds a moment using the settings of the current calendar: timezone and language.
                // Accepts anything the vanilla moment() constructor accepts.
                t.moment = function () {
                    var mom;

                    if (options.timezone === 'local') {
                        mom = fc.moment.apply(null, arguments);

                        // Force the moment to be local, because fc.moment doesn't guarantee it.
                        if (mom.hasTime()) { // don't give ambiguously-timed moments a local zone
                            mom.local();
                        }
                    } else if (options.timezone === 'UTC') {
                        mom = fc.moment.utc.apply(null, arguments); // process as UTC
                    } else {
                        mom = fc.moment.parseZone.apply(null, arguments); // let the input decide the zone
                    }

                    if ('_locale' in mom) { // moment 2.8 and above
                        mom._locale = localeData;
                    } else { // pre-moment-2.8
                        mom._lang = localeData;
                    }

                    return mom;
                };


                // Returns a boolean about whether or not the calendar knows how to calculate
                // the timezone offset of arbitrary dates in the current timezone.
                t.getIsAmbigTimezone = function () {
                    return options.timezone !== 'local' && options.timezone !== 'UTC';
                };


                // Returns a copy of the given date in the current timezone of it is ambiguously zoned.
                // This will also give the date an unambiguous time.
                t.rezoneDate = function (date) {
                    return t.moment(date.toArray());
                };


                // Returns a moment for the current date, as defined by the client's computer,
                // or overridden by the `now` option.
                t.getNow = function () {
                    var now = options.now;
                    if (typeof now === 'function') {
                        now = now();
                    }
                    return t.moment(now);
                };


                // Calculates the week number for a moment according to the calendar's
                // `weekNumberCalculation` setting.
                t.calculateWeekNumber = function (mom) {
                    var calc = options.weekNumberCalculation;

                    if (typeof calc === 'function') {
                        return calc(mom);
                    } else if (calc === 'local') {
                        return mom.week();
                    } else if (calc.toUpperCase() === 'ISO') {
                        return mom.isoWeek();
                    }
                };


                // Get an event's normalized end date. If not present, calculate it from the defaults.
                t.getEventEnd = function (event) {
                    if (event.end) {
                        return event.end.clone();
                    } else {
                        return t.getDefaultEventEnd(event.allDay, event.start);
                    }
                };


                // Given an event's allDay status and start date, return swhat its fallback end date should be.
                t.getDefaultEventEnd = function (allDay, start) { // TODO: rename to computeDefaultEventEnd
                    var end = start.clone();

                    if (allDay) {
                        end.stripTime().add(t.defaultAllDayEventDuration);
                    } else {
                        end.add(t.defaultTimedEventDuration);
                    }

                    if (t.getIsAmbigTimezone()) {
                        end.stripZone(); // we don't know what the tzo should be
                    }

                    return end;
                };


                // Produces a human-readable string for the given duration.
                // Side-effect: changes the locale of the given duration.
                function humanizeDuration(duration) {
                    return (duration.locale || duration.lang).call(duration, options.lang) // works moment-pre-2.8
                            .humanize();
                }



                // Imports
                // -----------------------------------------------------------------------------------


                EventManager.call(t, options);
                var isFetchNeeded = t.isFetchNeeded;
                var fetchEvents = t.fetchEvents;



                // Locals
                // -----------------------------------------------------------------------------------


                var _element = element[0];
                var header;
                var headerElement;
                var content;
                var tm; // for making theme classes
                var viewSpecCache = {};
                var currentView;
                var suggestedViewHeight;
                var windowResizeProxy; // wraps the windowResize function
                var ignoreWindowResize = 0;
                var date;
                var events = [];



                // Main Rendering
                // -----------------------------------------------------------------------------------


                if (options.defaultDate != null) {
                    date = t.moment(options.defaultDate);
                } else {
                    date = t.getNow();
                }


                function render(inc) {
                    if (!content) {
                        initialRender();
                    } else if (elementVisible()) {
                        // mainly for the public API
                        calcSize();
                        renderView(inc);
                    }
                }


                function initialRender() {
                    tm = options.theme ? 'ui' : 'fc';
                    element.addClass('fc');

                    if (options.isRTL) {
                        element.addClass('fc-rtl');
                    } else {
                        element.addClass('fc-ltr');
                    }

                    if (options.theme) {
                        element.addClass('ui-widget');
                    } else {
                        element.addClass('fc-unthemed');
                    }

                    content = $("<div class='fc-view-container'/>").prependTo(element);

                    header = new Header(t, options);
                    headerElement = header.render();
                    if (headerElement) {
                        element.prepend(headerElement);
                    }

                    changeView(options.defaultView);

                    if (options.handleWindowResize) {
                        windowResizeProxy = debounce(windowResize, options.windowResizeDelay); // prevents rapid calls
                        $(window).resize(windowResizeProxy);
                    }
                }


                function destroy() {

                    if (currentView) {
                        currentView.destroyView();
                    }

                    header.destroy();
                    content.remove();
                    element.removeClass('fc fc-ltr fc-rtl fc-unthemed ui-widget');

                    $(window).unbind('resize', windowResizeProxy);
                }


                function elementVisible() {
                    return element.is(':visible');
                }



                // View Rendering
                // -----------------------------------------------------------------------------------


                function changeView(viewType) {
                    renderView(0, viewType);
                }


                // Renders a view because of a date change, view-type change, or for the first time
                function renderView(delta, viewType) {
                    ignoreWindowResize++;

                    // if viewType is changing, destroy the old view
                    if (currentView && viewType && currentView.type !== viewType) {
                        header.deactivateButton(currentView.type);
                        freezeContentHeight(); // prevent a scroll jump when view element is removed
                        if (currentView.start) { // rendered before?
                            currentView.destroyView();
                        }
                        currentView.el.remove();
                        currentView = null;
                    }

                    // if viewType changed, or the view was never created, create a fresh view
                    if (!currentView && viewType) {
                        currentView = instantiateView(viewType);
                        currentView.el = $("<div class='fc-view fc-" + viewType + "-view' />").appendTo(content);
                        header.activateButton(viewType);
                    }

                    if (currentView) {

                        // let the view determine what the delta means
                        if (delta < 0) {
                            date = currentView.computePrevDate(date);
                        } else if (delta > 0) {
                            date = currentView.computeNextDate(date);
                        }

                        // render or rerender the view
                        if (
                                !currentView.start || // never rendered before
                                delta || // explicit date window change
                                !date.isWithin(currentView.intervalStart, currentView.intervalEnd) // implicit date window change
                                ) {
                            if (elementVisible()) {

                                freezeContentHeight();
                                if (currentView.start) { // rendered before?
                                    currentView.destroyView();
                                }
                                currentView.setDate(date);
                                currentView.renderView();
                                unfreezeContentHeight();

                                // need to do this after View::render, so dates are calculated
                                updateTitle();
                                updateTodayButton();

                                getAndRenderEvents();
                            }
                        }
                    }

                    unfreezeContentHeight(); // undo any lone freezeContentHeight calls
                    ignoreWindowResize--;
                }



                // View Instantiation
                // -----------------------------------------------------------------------------------


                // Given a view name for a custom view or a standard view, creates a ready-to-go View object
                function instantiateView(viewType) {
                    var spec = getViewSpec(viewType);

                    return new spec['class'](t, spec.options, viewType);
                }


                // Gets information about how to create a view
                function getViewSpec(requestedViewType) {
                    var allDefaultButtonText = options.defaultButtonText || {};
                    var allButtonText = options.buttonText || {};
                    var hash = options.views || {}; // the `views` option object
                    var viewType = requestedViewType;
                    var viewOptionsChain = [];
                    var viewOptions;
                    var viewClass;
                    var duration, unit, unitIsSingle = false;
                    var buttonText;

                    if (viewSpecCache[requestedViewType]) {
                        return viewSpecCache[requestedViewType];
                    }

                    function processSpecInput(input) {
                        if (typeof input === 'function') {
                            viewClass = input;
                        } else if (typeof input === 'object') {
                            $.extend(viewOptions, input);
                        }
                    }

                    // iterate up a view's spec ancestor chain util we find a class to instantiate
                    while (viewType && !viewClass) {
                        viewOptions = {}; // only for this specific view in the ancestry
                        processSpecInput(fcViews[viewType]); // $.fullCalendar.views, lower precedence
                        processSpecInput(hash[viewType]); // options at initialization, higher precedence
                        viewOptionsChain.unshift(viewOptions); // record older ancestors first
                        viewType = viewOptions.type;
                    }

                    viewOptionsChain.unshift({}); // jQuery's extend needs at least one arg
                    viewOptions = $.extend.apply($, viewOptionsChain); // combine all, newer ancestors overwritting old

                    if (viewClass) {

                        duration = viewOptions.duration || viewClass.duration;
                        if (duration) {
                            duration = moment.duration(duration);
                            unit = computeIntervalUnit(duration);
                            unitIsSingle = computeIntervalAs(unit, duration) === 1;
                        }

                        // options that are specified per the view's duration, like "week" or "day"
                        if (unitIsSingle && hash[unit]) {
                            viewOptions = $.extend({}, hash[unit], viewOptions); // lowest priority
                        }

                        // compute the final text for the button representing this view
                        buttonText =
                                allButtonText[requestedViewType] || // init options, like "agendaWeek"
                                (unitIsSingle ? allButtonText[unit] : null) || // init options, like "week"
                                allDefaultButtonText[requestedViewType] || // lang data, like "agendaWeek"
                                (unitIsSingle ? allDefaultButtonText[unit] : null) || // lang data, like "week"
                                viewOptions.buttonText ||
                                viewClass.buttonText ||
                                (duration ? humanizeDuration(duration) : null) ||
                                requestedViewType;

                        return (viewSpecCache[requestedViewType] = {
                            'class': viewClass,
                            options: viewOptions,
                            buttonText: buttonText
                        });
                    }
                }


                // Returns a boolean about whether the view is okay to instantiate at some point
                function isValidViewType(viewType) {
                    return Boolean(getViewSpec(viewType));
                }


                // Gets the text that should be displayed on a view's button in the header
                function getViewButtonText(viewType) {
                    var spec = getViewSpec(viewType);

                    if (spec) {
                        return spec.buttonText;
                    }
                }



                // Resizing
                // -----------------------------------------------------------------------------------


                t.getSuggestedViewHeight = function () {
                    if (suggestedViewHeight === undefined) {
                        calcSize();
                    }
                    return suggestedViewHeight;
                };


                t.isHeightAuto = function () {
                    return options.contentHeight === 'auto' || options.height === 'auto';
                };


                function updateSize(shouldRecalc) {
                    if (elementVisible()) {

                        if (shouldRecalc) {
                            _calcSize();
                        }

                        ignoreWindowResize++;
                        currentView.updateSize(true); // isResize=true. will poll getSuggestedViewHeight() and isHeightAuto()
                        ignoreWindowResize--;

                        return true; // signal success
                    }
                }


                function calcSize() {
                    if (elementVisible()) {
                        _calcSize();
                    }
                }


                function _calcSize() { // assumes elementVisible
                    if (typeof options.contentHeight === 'number') { // exists and not 'auto'
                        suggestedViewHeight = options.contentHeight;
                    } else if (typeof options.height === 'number') { // exists and not 'auto'
                        suggestedViewHeight = options.height - (headerElement ? headerElement.outerHeight(true) : 0);
                    } else {
                        suggestedViewHeight = Math.round(content.width() / Math.max(options.aspectRatio, .5));
                    }
                }


                function windowResize(ev) {
                    if (
                            !ignoreWindowResize &&
                            ev.target === window && // so we don't process jqui "resize" events that have bubbled up
                            currentView.start // view has already been rendered
                            ) {
                        if (updateSize(true)) {
                            currentView.trigger('windowResize', _element);
                        }
                    }
                }



                /* Event Fetching/Rendering
                 -----------------------------------------------------------------------------*/
                // TODO: going forward, most of this stuff should be directly handled by the view


                function refetchEvents() { // can be called as an API method
                    destroyEvents(); // so that events are cleared before user starts waiting for AJAX
                    fetchAndRenderEvents();
                }


                function renderEvents() { // destroys old events if previously rendered
                    if (elementVisible()) {
                        freezeContentHeight();
                        currentView.destroyViewEvents(); // no performance cost if never rendered
                        currentView.renderViewEvents(events);
                        unfreezeContentHeight();
                    }
                }


                function destroyEvents() {
                    freezeContentHeight();
                    currentView.destroyViewEvents();
                    unfreezeContentHeight();
                }


                function getAndRenderEvents() {
                    if (!options.lazyFetching || isFetchNeeded(currentView.start, currentView.end)) {
                        fetchAndRenderEvents();
                    } else {
                        renderEvents();
                    }
                }


                function fetchAndRenderEvents() {
                    fetchEvents(currentView.start, currentView.end);
                    // ... will call reportEvents
                    // ... which will call renderEvents
                }


                // called when event data arrives
                function reportEvents(_events) {
                    events = _events;
                    renderEvents();
                }


                // called when a single event's data has been changed
                function reportEventChange() {
                    renderEvents();
                }



                /* Header Updating
                 -----------------------------------------------------------------------------*/


                function updateTitle() {
                    header.updateTitle(currentView.computeTitle());
                }


                function updateTodayButton() {
                    var now = t.getNow();
                    if (now.isWithin(currentView.intervalStart, currentView.intervalEnd)) {
                        header.disableButton('today');
                    } else {
                        header.enableButton('today');
                    }
                }



                /* Selection
                 -----------------------------------------------------------------------------*/


                function select(start, end) {

                    start = t.moment(start);
                    if (end) {
                        end = t.moment(end);
                    } else if (start.hasTime()) {
                        end = start.clone().add(t.defaultTimedEventDuration);
                    } else {
                        end = start.clone().add(t.defaultAllDayEventDuration);
                    }

                    currentView.select({start: start, end: end}); // accepts a range
                }


                function unselect() { // safe to be called before renderView
                    if (currentView) {
                        currentView.unselect();
                    }
                }



                /* Date
                 -----------------------------------------------------------------------------*/


                function prev() {
                    renderView(-1);
                }


                function next() {
                    renderView(1);
                }


                function prevYear() {
                    date.add(-1, 'years');
                    renderView();
                }


                function nextYear() {
                    date.add(1, 'years');
                    renderView();
                }


                function today() {
                    date = t.getNow();
                    renderView();
                }


                function gotoDate(dateInput) {
                    date = t.moment(dateInput);
                    renderView();
                }


                function incrementDate(delta) {
                    date.add(moment.duration(delta));
                    renderView();
                }


                // Forces navigation to a view for the given date.
                // `viewType` can be a specific view name or a generic one like "week" or "day".
                function zoomTo(newDate, viewType) {
                    var viewStr;
                    var match;

                    if (!viewType || !isValidViewType(viewType)) { // a general view name, or "auto"
                        viewType = viewType || 'day';
                        viewStr = header.getViewsWithButtons().join(' '); // space-separated string of all the views in the header

                        // try to match a general view name, like "week", against a specific one, like "agendaWeek"
                        match = viewStr.match(new RegExp('\\w+' + capitaliseFirstLetter(viewType)));

                        // fall back to the day view being used in the header
                        if (!match) {
                            match = viewStr.match(/\w+Day/);
                        }

                        viewType = match ? match[0] : 'agendaDay'; // fall back to agendaDay
                    }

                    date = newDate;
                    changeView(viewType);
                }


                function getDate() {
                    return date.clone();
                }



                /* Height "Freezing"
                 -----------------------------------------------------------------------------*/


                function freezeContentHeight() {
                    content.css({
                        width: '100%',
                        height: content.height(),
                        overflow: 'hidden'
                    });
                }


                function unfreezeContentHeight() {
                    content.css({
                        width: '',
                        height: '',
                        overflow: ''
                    });
                }



                /* Misc
                 -----------------------------------------------------------------------------*/


                function getCalendar() {
                    return t;
                }


                function getView() {
                    return currentView;
                }


                function option(name, value) {
                    if (value === undefined) {
                        return options[name];
                    }
                    if (name == 'height' || name == 'contentHeight' || name == 'aspectRatio') {
                        options[name] = value;
                        updateSize(true); // true = allow recalculation of height
                    }
                }


                function trigger(name, thisObj) {
                    if (options[name]) {
                        return options[name].apply(
                                thisObj || _element,
                                Array.prototype.slice.call(arguments, 2)
                                );
                    }
                }

            }

            /* Top toolbar area with buttons and title
             ----------------------------------------------------------------------------------------------------------------------*/
// TODO: rename all header-related things to "toolbar"

            function Header(calendar, options) {
                var t = this;

                // exports
                t.render = render;
                t.destroy = destroy;
                t.updateTitle = updateTitle;
                t.activateButton = activateButton;
                t.deactivateButton = deactivateButton;
                t.disableButton = disableButton;
                t.enableButton = enableButton;
                t.getViewsWithButtons = getViewsWithButtons;

                // locals
                var el = $();
                var viewsWithButtons = [];
                var tm;


                function render() {
                    var sections = options.header;

                    tm = options.theme ? 'ui' : 'fc';

                    if (sections) {
                        el = $("<div class='fc-toolbar'/>")
                                .append(renderSection('left'))
                                .append(renderSection('right'))
                                .append(renderSection('center'))
                                .append('<div class="fc-clear"/>');

                        return el;
                    }
                }


                function destroy() {
                    el.remove();
                }


                function renderSection(position) {
                    var sectionEl = $('<div class="fc-' + position + '"/>');
                    var buttonStr = options.header[position];

                    if (buttonStr) {
                        $.each(buttonStr.split(' '), function (i) {
                            var groupChildren = $();
                            var isOnlyButtons = true;
                            var groupEl;

                            $.each(this.split(','), function (j, buttonName) {
                                var buttonClick;
                                var themeIcon;
                                var normalIcon;
                                var defaultText;
                                var viewText; // highest priority
                                var customText;
                                var innerHtml;
                                var classes;
                                var button;

                                if (buttonName == 'title') {
                                    groupChildren = groupChildren.add($('<h2>&nbsp;</h2>')); // we always want it to take up height
                                    isOnlyButtons = false;
                                } else {
                                    if (calendar[buttonName]) { // a calendar method
                                        buttonClick = function () {
                                            calendar[buttonName]();
                                        };
                                    } else if (calendar.isValidViewType(buttonName)) { // a view type
                                        buttonClick = function () {
                                            calendar.changeView(buttonName);
                                        };
                                        viewsWithButtons.push(buttonName);
                                        viewText = calendar.getViewButtonText(buttonName);
                                    }
                                    if (buttonClick) {

                                        // smartProperty allows different text per view button (ex: "Agenda Week" vs "Basic Week")
                                        themeIcon = smartProperty(options.themeButtonIcons, buttonName);
                                        normalIcon = smartProperty(options.buttonIcons, buttonName);
                                        defaultText = smartProperty(options.defaultButtonText, buttonName); // from languages
                                        customText = smartProperty(options.buttonText, buttonName);

                                        if (viewText || customText) {
                                            innerHtml = htmlEscape(viewText || customText);
                                        } else if (themeIcon && options.theme) {
                                            innerHtml = "<span class='ui-icon ui-icon-" + themeIcon + "'></span>";
                                        } else if (normalIcon && !options.theme) {
                                            innerHtml = "<span class='fc-icon fc-icon-" + normalIcon + "'></span>";
                                        } else {
                                            innerHtml = htmlEscape(defaultText || buttonName);
                                        }

                                        classes = [
                                            'fc-' + buttonName + '-button',
                                            tm + '-button',
                                            tm + '-state-default'
                                        ];

                                        button = $(// type="button" so that it doesn't submit a form
                                                '<button type="button" class="' + classes.join(' ') + '">' +
                                                innerHtml +
                                                '</button>'
                                                )
                                                .click(function () {
                                                    // don't process clicks for disabled buttons
                                                    if (!button.hasClass(tm + '-state-disabled')) {

                                                        buttonClick();

                                                        // after the click action, if the button becomes the "active" tab, or disabled,
                                                        // it should never have a hover class, so remove it now.
                                                        if (
                                                                button.hasClass(tm + '-state-active') ||
                                                                button.hasClass(tm + '-state-disabled')
                                                                ) {
                                                            button.removeClass(tm + '-state-hover');
                                                        }
                                                    }
                                                })
                                                .mousedown(function () {
                                                    // the *down* effect (mouse pressed in).
                                                    // only on buttons that are not the "active" tab, or disabled
                                                    button
                                                            .not('.' + tm + '-state-active')
                                                            .not('.' + tm + '-state-disabled')
                                                            .addClass(tm + '-state-down');
                                                })
                                                .mouseup(function () {
                                                    // undo the *down* effect
                                                    button.removeClass(tm + '-state-down');
                                                })
                                                .hover(
                                                        function () {
                                                            // the *hover* effect.
                                                            // only on buttons that are not the "active" tab, or disabled
                                                            button
                                                                    .not('.' + tm + '-state-active')
                                                                    .not('.' + tm + '-state-disabled')
                                                                    .addClass(tm + '-state-hover');
                                                        },
                                                        function () {
                                                            // undo the *hover* effect
                                                            button
                                                                    .removeClass(tm + '-state-hover')
                                                                    .removeClass(tm + '-state-down'); // if mouseleave happens before mouseup
                                                        }
                                                );

                                        groupChildren = groupChildren.add(button);
                                    }
                                }
                            });

                            if (isOnlyButtons) {
                                groupChildren
                                        .first().addClass(tm + '-corner-left').end()
                                        .last().addClass(tm + '-corner-right').end();
                            }

                            if (groupChildren.length > 1) {
                                groupEl = $('<div/>');
                                if (isOnlyButtons) {
                                    groupEl.addClass('fc-button-group');
                                }
                                groupEl.append(groupChildren);
                                sectionEl.append(groupEl);
                            } else {
                                sectionEl.append(groupChildren); // 1 or 0 children
                            }
                        });
                    }

                    return sectionEl;
                }


                function updateTitle(text) {
                    el.find('h2').text(text);
                }


                function activateButton(buttonName) {
                    el.find('.fc-' + buttonName + '-button')
                            .addClass(tm + '-state-active');
                }


                function deactivateButton(buttonName) {
                    el.find('.fc-' + buttonName + '-button')
                            .removeClass(tm + '-state-active');
                }


                function disableButton(buttonName) {
                    el.find('.fc-' + buttonName + '-button')
                            .attr('disabled', 'disabled')
                            .addClass(tm + '-state-disabled');
                }


                function enableButton(buttonName) {
                    el.find('.fc-' + buttonName + '-button')
                            .removeAttr('disabled')
                            .removeClass(tm + '-state-disabled');
                }


                function getViewsWithButtons() {
                    return viewsWithButtons;
                }

            }

            fc.sourceNormalizers = [];
            fc.sourceFetchers = [];

            var ajaxDefaults = {
                dataType: 'json',
                cache: false
            };

            var eventGUID = 1;


            function EventManager(options) { // assumed to be a calendar
                var t = this;


                // exports
                t.isFetchNeeded = isFetchNeeded;
                t.fetchEvents = fetchEvents;
                t.addEventSource = addEventSource;
                t.removeEventSource = removeEventSource;
                t.updateEvent = updateEvent;
                t.renderEvent = renderEvent;
                t.removeEvents = removeEvents;
                t.clientEvents = clientEvents;
                t.mutateEvent = mutateEvent;
                t.normalizeEventDateProps = normalizeEventDateProps;
                t.ensureVisibleEventRange = ensureVisibleEventRange;


                // imports
                var trigger = t.trigger;
                var getView = t.getView;
                var reportEvents = t.reportEvents;


                // locals
                var stickySource = {events: []};
                var sources = [stickySource];
                var rangeStart, rangeEnd;
                var currentFetchID = 0;
                var pendingSourceCnt = 0;
                var loadingLevel = 0;
                var cache = []; // holds events that have already been expanded


                $.each(
                        (options.events ? [options.events] : []).concat(options.eventSources || []),
                        function (i, sourceInput) {
                            var source = buildEventSource(sourceInput);
                            if (source) {
                                sources.push(source);
                            }
                        }
                );



                /* Fetching
                 -----------------------------------------------------------------------------*/


                function isFetchNeeded(start, end) {
                    return !rangeStart || // nothing has been fetched yet?
                            // or, a part of the new range is outside of the old range? (after normalizing)
                            start.clone().stripZone() < rangeStart.clone().stripZone() ||
                            end.clone().stripZone() > rangeEnd.clone().stripZone();
                }


                function fetchEvents(start, end) {
                    rangeStart = start;
                    rangeEnd = end;
                    cache = [];
                    var fetchID = ++currentFetchID;
                    var len = sources.length;
                    pendingSourceCnt = len;
                    for (var i = 0; i < len; i++) {
                        fetchEventSource(sources[i], fetchID);
                    }
                }


                function fetchEventSource(source, fetchID) {
                    _fetchEventSource(source, function (eventInputs) {
                        var isArraySource = $.isArray(source.events);
                        var i, eventInput;
                        var abstractEvent;

                        if (fetchID == currentFetchID) {

                            if (eventInputs) {
                                for (i = 0; i < eventInputs.length; i++) {
                                    eventInput = eventInputs[i];

                                    if (isArraySource) { // array sources have already been convert to Event Objects
                                        abstractEvent = eventInput;
                                    } else {
                                        abstractEvent = buildEventFromInput(eventInput, source);
                                    }

                                    if (abstractEvent) { // not false (an invalid event)
                                        cache.push.apply(
                                                cache,
                                                expandEvent(abstractEvent) // add individual expanded events to the cache
                                                );
                                    }
                                }
                            }

                            pendingSourceCnt--;
                            if (!pendingSourceCnt) {
                                reportEvents(cache);
                            }
                        }
                    });
                }


                function _fetchEventSource(source, callback) {
                    var i;
                    var fetchers = fc.sourceFetchers;
                    var res;

                    for (i = 0; i < fetchers.length; i++) {
                        res = fetchers[i].call(
                                t, // this, the Calendar object
                                source,
                                rangeStart.clone(),
                                rangeEnd.clone(),
                                options.timezone,
                                callback
                                );

                        if (res === true) {
                            // the fetcher is in charge. made its own async request
                            return;
                        } else if (typeof res == 'object') {
                            // the fetcher returned a new source. process it
                            _fetchEventSource(res, callback);
                            return;
                        }
                    }

                    var events = source.events;
                    if (events) {
                        if ($.isFunction(events)) {
                            pushLoading();
                            events.call(
                                    t, // this, the Calendar object
                                    rangeStart.clone(),
                                    rangeEnd.clone(),
                                    options.timezone,
                                    function (events) {
                                        callback(events);
                                        popLoading();
                                    }
                            );
                        } else if ($.isArray(events)) {
                            callback(events);
                        } else {
                            callback();
                        }
                    } else {
                        var url = source.url;
                        if (url) {
                            var success = source.success;
                            var error = source.error;
                            var complete = source.complete;

                            // retrieve any outbound GET/POST $.ajax data from the options
                            var customData;
                            if ($.isFunction(source.data)) {
                                // supplied as a function that returns a key/value object
                                customData = source.data();
                            } else {
                                // supplied as a straight key/value object
                                customData = source.data;
                            }

                            // use a copy of the custom data so we can modify the parameters
                            // and not affect the passed-in object.
                            var data = $.extend({}, customData || {});

                            var startParam = firstDefined(source.startParam, options.startParam);
                            var endParam = firstDefined(source.endParam, options.endParam);
                            var timezoneParam = firstDefined(source.timezoneParam, options.timezoneParam);

                            if (startParam) {
                                data[startParam] = rangeStart.format();
                            }
                            if (endParam) {
                                data[endParam] = rangeEnd.format();
                            }
                            if (options.timezone && options.timezone != 'local') {
                                data[timezoneParam] = options.timezone;
                            }

                            pushLoading();
                            $.ajax($.extend({}, ajaxDefaults, source, {
                                data: data,
                                success: function (events) {
                                    events = events || [];
                                    var res = applyAll(success, this, arguments);
                                    if ($.isArray(res)) {
                                        events = res;
                                    }
                                    callback(events);
                                },
                                error: function () {
                                    applyAll(error, this, arguments);
                                    callback();
                                },
                                complete: function () {
                                    applyAll(complete, this, arguments);
                                    popLoading();
                                }
                            }));
                        } else {
                            callback();
                        }
                    }
                }



                /* Sources
                 -----------------------------------------------------------------------------*/


                function addEventSource(sourceInput) {
                    var source = buildEventSource(sourceInput);
                    if (source) {
                        sources.push(source);
                        pendingSourceCnt++;
                        fetchEventSource(source, currentFetchID); // will eventually call reportEvents
                    }
                }


                function buildEventSource(sourceInput) { // will return undefined if invalid source
                    var normalizers = fc.sourceNormalizers;
                    var source;
                    var i;

                    if ($.isFunction(sourceInput) || $.isArray(sourceInput)) {
                        source = {events: sourceInput};
                    } else if (typeof sourceInput === 'string') {
                        source = {url: sourceInput};
                    } else if (typeof sourceInput === 'object') {
                        source = $.extend({}, sourceInput); // shallow copy
                    }

                    if (source) {

                        // TODO: repeat code, same code for event classNames
                        if (source.className) {
                            if (typeof source.className === 'string') {
                                source.className = source.className.split(/\s+/);
                            }
                            // otherwise, assumed to be an array
                        } else {
                            source.className = [];
                        }

                        // for array sources, we convert to standard Event Objects up front
                        if ($.isArray(source.events)) {
                            source.origArray = source.events; // for removeEventSource
                            source.events = $.map(source.events, function (eventInput) {
                                return buildEventFromInput(eventInput, source);
                            });
                        }

                        for (i = 0; i < normalizers.length; i++) {
                            normalizers[i].call(t, source);
                        }

                        return source;
                    }
                }


                function removeEventSource(source) {
                    sources = $.grep(sources, function (src) {
                        return !isSourcesEqual(src, source);
                    });
                    // remove all client events from that source
                    cache = $.grep(cache, function (e) {
                        return !isSourcesEqual(e.source, source);
                    });
                    reportEvents(cache);
                }


                function isSourcesEqual(source1, source2) {
                    return source1 && source2 && getSourcePrimitive(source1) == getSourcePrimitive(source2);
                }


                function getSourcePrimitive(source) {
                    return (
                            (typeof source === 'object') ? // a normalized event source?
                            (source.origArray || source.googleCalendarId || source.url || source.events) : // get the primitive
                            null
                            ) ||
                            source; // the given argument *is* the primitive
                }



                /* Manipulation
                 -----------------------------------------------------------------------------*/


                // Only ever called from the externally-facing API
                function updateEvent(event) {

                    // massage start/end values, even if date string values
                    event.start = t.moment(event.start);
                    if (event.end) {
                        event.end = t.moment(event.end);
                    } else {
                        event.end = null;
                    }

                    mutateEvent(event, getMiscEventProps(event)); // will handle start/end/allDay normalization
                    reportEvents(cache); // reports event modifications (so we can redraw)
                }


                // Returns a hash of misc event properties that should be copied over to related events.
                function getMiscEventProps(event) {
                    var props = {};

                    $.each(event, function (name, val) {
                        if (isMiscEventPropName(name)) {
                            if (val !== undefined && isAtomic(val)) { // a defined non-object
                                props[name] = val;
                            }
                        }
                    });

                    return props;
                }

                // non-date-related, non-id-related, non-secret
                function isMiscEventPropName(name) {
                    return !/^_|^(id|allDay|start|end)$/.test(name);
                }


                // returns the expanded events that were created
                function renderEvent(eventInput, stick) {
                    var abstractEvent = buildEventFromInput(eventInput);
                    var events;
                    var i, event;

                    if (abstractEvent) { // not false (a valid input)
                        events = expandEvent(abstractEvent);

                        for (i = 0; i < events.length; i++) {
                            event = events[i];

                            if (!event.source) {
                                if (stick) {
                                    stickySource.events.push(event);
                                    event.source = stickySource;
                                }
                                cache.push(event);
                            }
                        }

                        reportEvents(cache);

                        return events;
                    }

                    return [];
                }


                function removeEvents(filter) {
                    var eventID;
                    var i;

                    if (filter == null) { // null or undefined. remove all events
                        filter = function () {
                            return true;
                        }; // will always match
                    } else if (!$.isFunction(filter)) { // an event ID
                        eventID = filter + '';
                        filter = function (event) {
                            return event._id == eventID;
                        };
                    }

                    // Purge event(s) from our local cache
                    cache = $.grep(cache, filter, true); // inverse=true

                    // Remove events from array sources.
                    // This works because they have been converted to official Event Objects up front.
                    // (and as a result, event._id has been calculated).
                    for (i = 0; i < sources.length; i++) {
                        if ($.isArray(sources[i].events)) {
                            sources[i].events = $.grep(sources[i].events, filter, true);
                        }
                    }

                    reportEvents(cache);
                }


                function clientEvents(filter) {
                    if ($.isFunction(filter)) {
                        return $.grep(cache, filter);
                    } else if (filter != null) { // not null, not undefined. an event ID
                        filter += '';
                        return $.grep(cache, function (e) {
                            return e._id == filter;
                        });
                    }
                    return cache; // else, return all
                }



                /* Loading State
                 -----------------------------------------------------------------------------*/


                function pushLoading() {
                    if (!(loadingLevel++)) {
                        trigger('loading', null, true, getView());
                    }
                }


                function popLoading() {
                    if (!(--loadingLevel)) {
                        trigger('loading', null, false, getView());
                    }
                }



                /* Event Normalization
                 -----------------------------------------------------------------------------*/


                // Given a raw object with key/value properties, returns an "abstract" Event object.
                // An "abstract" event is an event that, if recurring, will not have been expanded yet.
                // Will return `false` when input is invalid.
                // `source` is optional
                function buildEventFromInput(input, source) {
                    var out = {};
                    var start, end;
                    var allDay;

                    if (options.eventDataTransform) {
                        input = options.eventDataTransform(input);
                    }
                    if (source && source.eventDataTransform) {
                        input = source.eventDataTransform(input);
                    }

                    // Copy all properties over to the resulting object.
                    // The special-case properties will be copied over afterwards.
                    $.extend(out, input);

                    if (source) {
                        out.source = source;
                    }

                    out._id = input._id || (input.id === undefined ? '_fc' + eventGUID++ : input.id + '');

                    if (input.className) {
                        if (typeof input.className == 'string') {
                            out.className = input.className.split(/\s+/);
                        } else { // assumed to be an array
                            out.className = input.className;
                        }
                    } else {
                        out.className = [];
                    }

                    start = input.start || input.date; // "date" is an alias for "start"
                    end = input.end;

                    // parse as a time (Duration) if applicable
                    if (isTimeString(start)) {
                        start = moment.duration(start);
                    }
                    if (isTimeString(end)) {
                        end = moment.duration(end);
                    }

                    if (input.dow || moment.isDuration(start) || moment.isDuration(end)) {

                        // the event is "abstract" (recurring) so don't calculate exact start/end dates just yet
                        out.start = start ? moment.duration(start) : null; // will be a Duration or null
                        out.end = end ? moment.duration(end) : null; // will be a Duration or null
                        out._recurring = true; // our internal marker
                    } else {

                        if (start) {
                            start = t.moment(start);
                            if (!start.isValid()) {
                                return false;
                            }
                        }

                        if (end) {
                            end = t.moment(end);
                            if (!end.isValid()) {
                                end = null; // let defaults take over
                            }
                        }

                        allDay = input.allDay;
                        if (allDay === undefined) { // still undefined? fallback to default
                            allDay = firstDefined(
                                    source ? source.allDayDefault : undefined,
                                    options.allDayDefault
                                    );
                            // still undefined? normalizeEventDateProps will calculate it
                        }

                        assignDatesToEvent(start, end, allDay, out);
                    }

                    return out;
                }


                // Normalizes and assigns the given dates to the given partially-formed event object.
                // NOTE: mutates the given start/end moments. does not make a copy.
                function assignDatesToEvent(start, end, allDay, event) {
                    event.start = start;
                    event.end = end;
                    event.allDay = allDay;
                    normalizeEventDateProps(event);
                    backupEventDates(event);
                }


                // Ensures the allDay property exists.
                // Ensures the start/end dates are consistent with allDay and forceEventDuration.
                // Accepts an Event object, or a plain object with event-ish properties.
                // NOTE: Will modify the given object.
                function normalizeEventDateProps(props) {

                    if (props.allDay == null) {
                        props.allDay = !(props.start.hasTime() || (props.end && props.end.hasTime()));
                    }

                    if (props.allDay) {
                        props.start.stripTime();
                        if (props.end) {
                            props.end.stripTime();
                        }
                    } else {
                        if (!props.start.hasTime()) {
                            props.start = t.rezoneDate(props.start); // will also give it a 00:00 time
                        }
                        if (props.end && !props.end.hasTime()) {
                            props.end = t.rezoneDate(props.end); // will also give it a 00:00 time
                        }
                    }

                    if (props.end && !props.end.isAfter(props.start)) {
                        props.end = null;
                    }

                    if (!props.end) {
                        if (options.forceEventDuration) {
                            props.end = t.getDefaultEventEnd(props.allDay, props.start);
                        } else {
                            props.end = null;
                        }
                    }
                }


                // If `range` is a proper range with a start and end, returns the original object.
                // If missing an end, computes a new range with an end, computing it as if it were an event.
                // TODO: make this a part of the event -> eventRange system
                function ensureVisibleEventRange(range) {
                    var allDay;

                    if (!range.end) {

                        allDay = range.allDay; // range might be more event-ish than we think
                        if (allDay == null) {
                            allDay = !range.start.hasTime();
                        }

                        range = {
                            start: range.start,
                            end: t.getDefaultEventEnd(allDay, range.start)
                        };
                    }
                    return range;
                }


                // If the given event is a recurring event, break it down into an array of individual instances.
                // If not a recurring event, return an array with the single original event.
                // If given a falsy input (probably because of a failed buildEventFromInput call), returns an empty array.
                // HACK: can override the recurring window by providing custom rangeStart/rangeEnd (for businessHours).
                function expandEvent(abstractEvent, _rangeStart, _rangeEnd) {
                    var events = [];
                    var dowHash;
                    var dow;
                    var i;
                    var date;
                    var startTime, endTime;
                    var start, end;
                    var event;

                    _rangeStart = _rangeStart || rangeStart;
                    _rangeEnd = _rangeEnd || rangeEnd;

                    if (abstractEvent) {
                        if (abstractEvent._recurring) {

                            // make a boolean hash as to whether the event occurs on each day-of-week
                            if ((dow = abstractEvent.dow)) {
                                dowHash = {};
                                for (i = 0; i < dow.length; i++) {
                                    dowHash[dow[i]] = true;
                                }
                            }

                            // iterate through every day in the current range
                            date = _rangeStart.clone().stripTime(); // holds the date of the current day
                            while (date.isBefore(_rangeEnd)) {

                                if (!dowHash || dowHash[date.day()]) { // if everyday, or this particular day-of-week

                                    startTime = abstractEvent.start; // the stored start and end properties are times (Durations)
                                    endTime = abstractEvent.end; // "
                                    start = date.clone();
                                    end = null;

                                    if (startTime) {
                                        start = start.time(startTime);
                                    }
                                    if (endTime) {
                                        end = date.clone().time(endTime);
                                    }

                                    event = $.extend({}, abstractEvent); // make a copy of the original
                                    assignDatesToEvent(
                                            start, end,
                                            !startTime && !endTime, // allDay?
                                            event
                                            );
                                    events.push(event);
                                }

                                date.add(1, 'days');
                            }
                        } else {
                            events.push(abstractEvent); // return the original event. will be a one-item array
                        }
                    }

                    return events;
                }



                /* Event Modification Math
                 -----------------------------------------------------------------------------------------*/


                // Modifies an event and all related events by applying the given properties.
                // Special date-diffing logic is used for manipulation of dates.
                // If `props` does not contain start/end dates, the updated values are assumed to be the event's current start/end.
                // All date comparisons are done against the event's pristine _start and _end dates.
                // Returns an object with delta information and a function to undo all operations.
                //
                function mutateEvent(event, props) {
                    var miscProps = {};
                    var clearEnd;
                    var dateDelta;
                    var durationDelta;
                    var undoFunc;

                    props = props || {};

                    // ensure new date-related values to compare against
                    if (!props.start) {
                        props.start = event.start.clone();
                    }
                    if (props.end === undefined) {
                        props.end = event.end ? event.end.clone() : null;
                    }
                    if (props.allDay == null) { // is null or undefined?
                        props.allDay = event.allDay;
                    }

                    normalizeEventDateProps(props); // massages start/end/allDay

                    // clear the end date if explicitly changed to null
                    clearEnd = event._end !== null && props.end === null;

                    // compute the delta for moving the start and end dates together
                    if (props.allDay) {
                        dateDelta = diffDay(props.start, event._start); // whole-day diff from start-of-day
                    } else {
                        dateDelta = diffDayTime(props.start, event._start);
                    }

                    // compute the delta for moving the end date (after applying dateDelta)
                    if (!clearEnd && props.end) {
                        durationDelta = diffDayTime(
                                // new duration
                                props.end,
                                props.start
                                ).subtract(diffDayTime(
                                // subtract old duration
                                event._end || t.getDefaultEventEnd(event._allDay, event._start),
                                event._start
                                ));
                    }

                    // gather all non-date-related properties
                    $.each(props, function (name, val) {
                        if (isMiscEventPropName(name)) {
                            if (val !== undefined) {
                                miscProps[name] = val;
                            }
                        }
                    });

                    // apply the operations to the event and all related events
                    undoFunc = mutateEvents(
                            clientEvents(event._id), // get events with this ID
                            clearEnd,
                            props.allDay,
                            dateDelta,
                            durationDelta,
                            miscProps
                            );

                    return {
                        dateDelta: dateDelta,
                        durationDelta: durationDelta,
                        undo: undoFunc
                    };
                }


                // Modifies an array of events in the following ways (operations are in order):
                // - clear the event's `end`
                // - convert the event to allDay
                // - add `dateDelta` to the start and end
                // - add `durationDelta` to the event's duration
                // - assign `miscProps` to the event
                //
                // Returns a function that can be called to undo all the operations.
                //
                // TODO: don't use so many closures. possible memory issues when lots of events with same ID.
                //
                function mutateEvents(events, clearEnd, allDay, dateDelta, durationDelta, miscProps) {
                    var isAmbigTimezone = t.getIsAmbigTimezone();
                    var undoFunctions = [];

                    // normalize zero-length deltas to be null
                    if (dateDelta && !dateDelta.valueOf()) {
                        dateDelta = null;
                    }
                    if (durationDelta && !durationDelta.valueOf()) {
                        durationDelta = null;
                    }

                    $.each(events, function (i, event) {
                        var oldProps;
                        var newProps;

                        // build an object holding all the old values, both date-related and misc.
                        // for the undo function.
                        oldProps = {
                            start: event.start.clone(),
                            end: event.end ? event.end.clone() : null,
                            allDay: event.allDay
                        };
                        $.each(miscProps, function (name) {
                            oldProps[name] = event[name];
                        });

                        // new date-related properties. work off the original date snapshot.
                        // ok to use references because they will be thrown away when backupEventDates is called.
                        newProps = {
                            start: event._start,
                            end: event._end,
                            allDay: event._allDay
                        };

                        if (clearEnd) {
                            newProps.end = null;
                        }

                        newProps.allDay = allDay;

                        normalizeEventDateProps(newProps); // massages start/end/allDay

                        if (dateDelta) {
                            newProps.start.add(dateDelta);
                            if (newProps.end) {
                                newProps.end.add(dateDelta);
                            }
                        }

                        if (durationDelta) {
                            if (!newProps.end) {
                                newProps.end = t.getDefaultEventEnd(newProps.allDay, newProps.start);
                            }
                            newProps.end.add(durationDelta);
                        }

                        // if the dates have changed, and we know it is impossible to recompute the
                        // timezone offsets, strip the zone.
                        if (
                                isAmbigTimezone &&
                                !newProps.allDay &&
                                (dateDelta || durationDelta)
                                ) {
                            newProps.start.stripZone();
                            if (newProps.end) {
                                newProps.end.stripZone();
                            }
                        }

                        $.extend(event, miscProps, newProps); // copy over misc props, then date-related props
                        backupEventDates(event); // regenerate internal _start/_end/_allDay

                        undoFunctions.push(function () {
                            $.extend(event, oldProps);
                            backupEventDates(event); // regenerate internal _start/_end/_allDay
                        });
                    });

                    return function () {
                        for (var i = 0; i < undoFunctions.length; i++) {
                            undoFunctions[i]();
                        }
                    };
                }


                /* Business Hours
                 -----------------------------------------------------------------------------------------*/

                t.getBusinessHoursEvents = getBusinessHoursEvents;


                // Returns an array of events as to when the business hours occur in the given view.
                // Abuse of our event system :(
                function getBusinessHoursEvents() {
                    var optionVal = options.businessHours;
                    var defaultVal = {
                        className: 'fc-nonbusiness',
                        start: '09:00',
                        end: '17:00',
                        dow: [1, 2, 3, 4, 5], // monday - friday
                        rendering: 'inverse-background'
                    };
                    var view = t.getView();
                    var eventInput;

                    if (optionVal) {
                        if (typeof optionVal === 'object') {
                            // option value is an object that can override the default business hours
                            eventInput = $.extend({}, defaultVal, optionVal);
                        } else {
                            // option value is `true`. use default business hours
                            eventInput = defaultVal;
                        }
                    }

                    if (eventInput) {
                        return expandEvent(
                                buildEventFromInput(eventInput),
                                view.start,
                                view.end
                                );
                    }

                    return [];
                }


                /* Overlapping / Constraining
                 -----------------------------------------------------------------------------------------*/

                t.isEventRangeAllowed = isEventRangeAllowed;
                t.isSelectionRangeAllowed = isSelectionRangeAllowed;
                t.isExternalDropRangeAllowed = isExternalDropRangeAllowed;


                function isEventRangeAllowed(range, event) {
                    var source = event.source || {};
                    var constraint = firstDefined(
                            event.constraint,
                            source.constraint,
                            options.eventConstraint
                            );
                    var overlap = firstDefined(
                            event.overlap,
                            source.overlap,
                            options.eventOverlap
                            );

                    range = ensureVisibleEventRange(range); // ensure a proper range with an end for isRangeAllowed

                    return isRangeAllowed(range, constraint, overlap, event);
                }


                function isSelectionRangeAllowed(range) {
                    return isRangeAllowed(range, options.selectConstraint, options.selectOverlap);
                }


                // when `eventProps` is defined, consider this an event.
                // `eventProps` can contain misc non-date-related info about the event.
                function isExternalDropRangeAllowed(range, eventProps) {
                    var eventInput;
                    var event;

                    // note: very similar logic is in View's reportExternalDrop
                    if (eventProps) {
                        eventInput = $.extend({}, eventProps, range);
                        event = expandEvent(buildEventFromInput(eventInput))[0];
                    }

                    if (event) {
                        return isEventRangeAllowed(range, event);
                    } else { // treat it as a selection

                        range = ensureVisibleEventRange(range); // ensure a proper range with an end for isSelectionRangeAllowed

                        return isSelectionRangeAllowed(range);
                    }
                }


                // Returns true if the given range (caused by an event drop/resize or a selection) is allowed to exist
                // according to the constraint/overlap settings.
                // `event` is not required if checking a selection.
                function isRangeAllowed(range, constraint, overlap, event) {
                    var constraintEvents;
                    var anyContainment;
                    var i, otherEvent;
                    var otherOverlap;

                    // normalize. fyi, we're normalizing in too many places :(
                    range = {
                        start: range.start.clone().stripZone(),
                        end: range.end.clone().stripZone()
                    };

                    // the range must be fully contained by at least one of produced constraint events
                    if (constraint != null) {

                        // not treated as an event! intermediate data structure
                        // TODO: use ranges in the future
                        constraintEvents = constraintToEvents(constraint);

                        anyContainment = false;
                        for (i = 0; i < constraintEvents.length; i++) {
                            if (eventContainsRange(constraintEvents[i], range)) {
                                anyContainment = true;
                                break;
                            }
                        }

                        if (!anyContainment) {
                            return false;
                        }
                    }

                    for (i = 0; i < cache.length; i++) { // loop all events and detect overlap
                        otherEvent = cache[i];

                        // don't compare the event to itself or other related [repeating] events
                        if (event && event._id === otherEvent._id) {
                            continue;
                        }

                        // there needs to be an actual intersection before disallowing anything
                        if (eventIntersectsRange(otherEvent, range)) {

                            // evaluate overlap for the given range and short-circuit if necessary
                            if (overlap === false) {
                                return false;
                            } else if (typeof overlap === 'function' && !overlap(otherEvent, event)) {
                                return false;
                            }

                            // if we are computing if the given range is allowable for an event, consider the other event's
                            // EventObject-specific or Source-specific `overlap` property
                            if (event) {
                                otherOverlap = firstDefined(
                                        otherEvent.overlap,
                                        (otherEvent.source || {}).overlap
                                        // we already considered the global `eventOverlap`
                                        );
                                if (otherOverlap === false) {
                                    return false;
                                }
                                if (typeof otherOverlap === 'function' && !otherOverlap(event, otherEvent)) {
                                    return false;
                                }
                            }
                        }
                    }

                    return true;
                }


                // Given an event input from the API, produces an array of event objects. Possible event inputs:
                // 'businessHours'
                // An event ID (number or string)
                // An object with specific start/end dates or a recurring event (like what businessHours accepts)
                function constraintToEvents(constraintInput) {

                    if (constraintInput === 'businessHours') {
                        return getBusinessHoursEvents();
                    }

                    if (typeof constraintInput === 'object') {
                        return expandEvent(buildEventFromInput(constraintInput));
                    }

                    return clientEvents(constraintInput); // probably an ID
                }


                // Does the event's date range fully contain the given range?
                // start/end already assumed to have stripped zones :(
                function eventContainsRange(event, range) {
                    var eventStart = event.start.clone().stripZone();
                    var eventEnd = t.getEventEnd(event).stripZone();

                    return range.start >= eventStart && range.end <= eventEnd;
                }


                // Does the event's date range intersect with the given range?
                // start/end already assumed to have stripped zones :(
                function eventIntersectsRange(event, range) {
                    var eventStart = event.start.clone().stripZone();
                    var eventEnd = t.getEventEnd(event).stripZone();

                    return range.start < eventEnd && range.end > eventStart;
                }

            }


// updates the "backup" properties, which are preserved in order to compute diffs later on.
            function backupEventDates(event) {
                event._allDay = event.allDay;
                event._start = event.start.clone();
                event._end = event.end ? event.end.clone() : null;
            }

            /* An abstract class for the "basic" views, as well as month view. Renders one or more rows of day cells.
             ----------------------------------------------------------------------------------------------------------------------*/
// It is a manager for a DayGrid subcomponent, which does most of the heavy lifting.
// It is responsible for managing width/height.

            var BasicView = fcViews.basic = View.extend({

                dayGrid: null, // the main subcomponent that does most of the heavy lifting

                dayNumbersVisible: false, // display day numbers on each day cell?
                weekNumbersVisible: false, // display week numbers along the side?

                weekNumberWidth: null, // width of all the week-number cells running down the side

                headRowEl: null, // the fake row element of the day-of-week header


                initialize: function () {
                    this.dayGrid = new DayGrid(this);
                    this.coordMap = this.dayGrid.coordMap; // the view's date-to-cell mapping is identical to the subcomponent's
                },

                // Sets the display range and computes all necessary dates
                setRange: function (range) {
                    View.prototype.setRange.call(this, range); // call the super-method

                    this.dayGrid.breakOnWeeks = /year|month|week/.test(this.intervalUnit); // do before setRange
                    this.dayGrid.setRange(range);
                },

                // Compute the value to feed into setRange. Overrides superclass.
                computeRange: function (date) {
                    var range = View.prototype.computeRange.call(this, date); // get value from the super-method

                    // year and month views should be aligned with weeks. this is already done for week
                    if (/year|month/.test(range.intervalUnit)) {
                        range.start.startOf('week');
                        range.start = this.skipHiddenDays(range.start);

                        // make end-of-week if not already
                        if (range.end.weekday()) {
                            range.end.add(1, 'week').startOf('week');
                            range.end = this.skipHiddenDays(range.end, -1, true); // exclusively move backwards
                        }
                    }

                    return range;
                },

                // Renders the view into `this.el`, which should already be assigned
                render: function () {

                    this.dayNumbersVisible = this.dayGrid.rowCnt > 1; // TODO: make grid responsible
                    this.weekNumbersVisible = this.opt('weekNumbers');
                    this.dayGrid.numbersVisible = this.dayNumbersVisible || this.weekNumbersVisible;

                    this.el.addClass('fc-basic-view').html(this.renderHtml());

                    this.headRowEl = this.el.find('thead .fc-row');

                    this.scrollerEl = this.el.find('.fc-day-grid-container');
                    this.dayGrid.coordMap.containerEl = this.scrollerEl; // constrain clicks/etc to the dimensions of the scroller

                    this.dayGrid.el = this.el.find('.fc-day-grid');
                    this.dayGrid.render(this.hasRigidRows());
                },

                // Make subcomponents ready for cleanup
                destroy: function () {
                    this.dayGrid.destroy();
                    View.prototype.destroy.call(this); // call the super-method
                },

                // Builds the HTML skeleton for the view.
                // The day-grid component will render inside of a container defined by this HTML.
                renderHtml: function () {
                    return '' +
                            '<table>' +
                            '<thead>' +
                            '<tr>' +
                            '<td class="' + this.widgetHeaderClass + '">' +
                            this.dayGrid.headHtml() + // render the day-of-week headers
                            '</td>' +
                            '</tr>' +
                            '</thead>' +
                            '<tbody>' +
                            '<tr>' +
                            '<td class="' + this.widgetContentClass + '">' +
                            '<div class="fc-day-grid-container">' +
                            '<div class="fc-day-grid"/>' +
                            '</div>' +
                            '</td>' +
                            '</tr>' +
                            '</tbody>' +
                            '</table>';
                },

                // Generates the HTML that will go before the day-of week header cells.
                // Queried by the DayGrid subcomponent when generating rows. Ordering depends on isRTL.
                headIntroHtml: function () {
                    if (this.weekNumbersVisible) {
                        return '' +
                                '<th class="fc-week-number ' + this.widgetHeaderClass + '" ' + this.weekNumberStyleAttr() + '>' +
                                '<span>' + // needed for matchCellWidths
                                htmlEscape(this.opt('weekNumberTitle')) +
                                '</span>' +
                                '</th>';
                    }
                },

                // Generates the HTML that will go before content-skeleton cells that display the day/week numbers.
                // Queried by the DayGrid subcomponent. Ordering depends on isRTL.
                numberIntroHtml: function (row) {
                    if (this.weekNumbersVisible) {
                        return '' +
                                '<td class="fc-week-number" ' + this.weekNumberStyleAttr() + '>' +
                                '<span>' + // needed for matchCellWidths
                                this.calendar.calculateWeekNumber(this.dayGrid.getCell(row, 0).start) +
                                '</span>' +
                                '</td>';
                    }
                },

                // Generates the HTML that goes before the day bg cells for each day-row.
                // Queried by the DayGrid subcomponent. Ordering depends on isRTL.
                dayIntroHtml: function () {
                    if (this.weekNumbersVisible) {
                        return '<td class="fc-week-number ' + this.widgetContentClass + '" ' +
                                this.weekNumberStyleAttr() + '></td>';
                    }
                },

                // Generates the HTML that goes before every other type of row generated by DayGrid. Ordering depends on isRTL.
                // Affects helper-skeleton and highlight-skeleton rows.
                introHtml: function () {
                    if (this.weekNumbersVisible) {
                        return '<td class="fc-week-number" ' + this.weekNumberStyleAttr() + '></td>';
                    }
                },

                // Generates the HTML for the <td>s of the "number" row in the DayGrid's content skeleton.
                // The number row will only exist if either day numbers or week numbers are turned on.
                numberCellHtml: function (cell) {
                    var date = cell.start;
                    var classes;

                    if (!this.dayNumbersVisible) { // if there are week numbers but not day numbers
                        return '<td/>'; //  will create an empty space above events :(
                    }

                    classes = this.dayGrid.getDayClasses(date);
                    classes.unshift('fc-day-number');

                    return '' +
                            '<td class="' + classes.join(' ') + '" data-date="' + date.format() + '">' +
                            date.date() +
                            '</td>';
                },

                // Generates an HTML attribute string for setting the width of the week number column, if it is known
                weekNumberStyleAttr: function () {
                    if (this.weekNumberWidth !== null) {
                        return 'style="width:' + this.weekNumberWidth + 'px"';
                    }
                    return '';
                },

                // Determines whether each row should have a constant height
                hasRigidRows: function () {
                    var eventLimit = this.opt('eventLimit');
                    return eventLimit && typeof eventLimit !== 'number';
                },

                /* Dimensions
                 ------------------------------------------------------------------------------------------------------------------*/


                // Refreshes the horizontal dimensions of the view
                updateWidth: function () {
                    if (this.weekNumbersVisible) {
                        // Make sure all week number cells running down the side have the same width.
                        // Record the width for cells created later.
                        this.weekNumberWidth = matchCellWidths(
                                this.el.find('.fc-week-number')
                                );
                    }
                },

                // Adjusts the vertical dimensions of the view to the specified values
                setHeight: function (totalHeight, isAuto) {
                    var eventLimit = this.opt('eventLimit');
                    var scrollerHeight;

                    // reset all heights to be natural
                    unsetScroller(this.scrollerEl);
                    uncompensateScroll(this.headRowEl);

                    this.dayGrid.destroySegPopover(); // kill the "more" popover if displayed

                    // is the event limit a constant level number?
                    if (eventLimit && typeof eventLimit === 'number') {
                        this.dayGrid.limitRows(eventLimit); // limit the levels first so the height can redistribute after
                    }

                    scrollerHeight = this.computeScrollerHeight(totalHeight);
                    this.setGridHeight(scrollerHeight, isAuto);

                    // is the event limit dynamically calculated?
                    if (eventLimit && typeof eventLimit !== 'number') {
                        this.dayGrid.limitRows(eventLimit); // limit the levels after the grid's row heights have been set
                    }

                    if (!isAuto && setPotentialScroller(this.scrollerEl, scrollerHeight)) { // using scrollbars?

                        compensateScroll(this.headRowEl, getScrollbarWidths(this.scrollerEl));

                        // doing the scrollbar compensation might have created text overflow which created more height. redo
                        scrollerHeight = this.computeScrollerHeight(totalHeight);
                        this.scrollerEl.height(scrollerHeight);

                        this.restoreScroll();
                    }
                },

                // Sets the height of just the DayGrid component in this view
                setGridHeight: function (height, isAuto) {
                    if (isAuto) {
                        undistributeHeight(this.dayGrid.rowEls); // let the rows be their natural height with no expanding
                    } else {
                        distributeHeight(this.dayGrid.rowEls, height, true); // true = compensate for height-hogging rows
                    }
                },

                /* Events
                 ------------------------------------------------------------------------------------------------------------------*/


                // Renders the given events onto the view and populates the segments array
                renderEvents: function (events) {
                    this.dayGrid.renderEvents(events);

                    this.updateHeight(); // must compensate for events that overflow the row
                },

                // Retrieves all segment objects that are rendered in the view
                getEventSegs: function () {
                    return this.dayGrid.getEventSegs();
                },

                // Unrenders all event elements and clears internal segment data
                destroyEvents: function () {
                    this.recordScroll(); // removing events will reduce height and mess with the scroll, so record beforehand
                    this.dayGrid.destroyEvents();

                    // we DON'T need to call updateHeight() because:
                    // A) a renderEvents() call always happens after this, which will eventually call updateHeight()
                    // B) in IE8, this causes a flash whenever events are rerendered
                },

                /* Dragging (for both events and external elements)
                 ------------------------------------------------------------------------------------------------------------------*/


                // A returned value of `true` signals that a mock "helper" event has been rendered.
                renderDrag: function (dropLocation, seg) {
                    return this.dayGrid.renderDrag(dropLocation, seg);
                },

                destroyDrag: function () {
                    this.dayGrid.destroyDrag();
                },

                /* Selection
                 ------------------------------------------------------------------------------------------------------------------*/


                // Renders a visual indication of a selection
                renderSelection: function (range) {
                    this.dayGrid.renderSelection(range);
                },

                // Unrenders a visual indications of a selection
                destroySelection: function () {
                    this.dayGrid.destroySelection();
                }

            });

            /* A month view with day cells running in rows (one-per-week) and columns
             ----------------------------------------------------------------------------------------------------------------------*/

            setDefaults({
                fixedWeekCount: true
            });

            var MonthView = fcViews.month = BasicView.extend({

                // Produces information about what range to display
                computeRange: function (date) {
                    var range = BasicView.prototype.computeRange.call(this, date); // get value from super-method

                    if (this.isFixedWeeks()) {
                        // ensure 6 weeks
                        range.end.add(
                                6 - range.end.diff(range.start, 'weeks'),
                                'weeks'
                                );
                    }

                    return range;
                },

                // Overrides the default BasicView behavior to have special multi-week auto-height logic
                setGridHeight: function (height, isAuto) {

                    isAuto = isAuto || this.opt('weekMode') === 'variable'; // LEGACY: weekMode is deprecated

                    // if auto, make the height of each row the height that it would be if there were 6 weeks
                    if (isAuto) {
                        height *= this.rowCnt / 6;
                    }

                    distributeHeight(this.dayGrid.rowEls, height, !isAuto); // if auto, don't compensate for height-hogging rows
                },

                isFixedWeeks: function () {
                    var weekMode = this.opt('weekMode'); // LEGACY: weekMode is deprecated
                    if (weekMode) {
                        return weekMode === 'fixed'; // if any other type of weekMode, assume NOT fixed
                    }

                    return this.opt('fixedWeekCount');
                }

            });

            MonthView.duration = {months: 1};

            /* A week view with simple day cells running horizontally
             ----------------------------------------------------------------------------------------------------------------------*/

            fcViews.basicWeek = {
                type: 'basic',
                duration: {weeks: 1}
            };
            /* A view with a single simple day cell
             ----------------------------------------------------------------------------------------------------------------------*/

            fcViews.basicDay = {
                type: 'basic',
                duration: {days: 1}
            };
            /* An abstract class for all agenda-related views. Displays one more columns with time slots running vertically.
             ----------------------------------------------------------------------------------------------------------------------*/
// Is a manager for the TimeGrid subcomponent and possibly the DayGrid subcomponent (if allDaySlot is on).
// Responsible for managing width/height.

            setDefaults({
                allDaySlot: true,
                allDayText: 'all-day',
                scrollTime: '06:00:00',
                slotDuration: '00:30:00',
                minTime: '00:00:00',
                maxTime: '24:00:00',
                slotEventOverlap: true
            });

            var AGENDA_ALL_DAY_EVENT_LIMIT = 5;

            fcViews.agenda = View.extend({// AgendaView

                timeGrid: null, // the main time-grid subcomponent of this view
                dayGrid: null, // the "all-day" subcomponent. if all-day is turned off, this will be null

                axisWidth: null, // the width of the time axis running down the side

                noScrollRowEls: null, // set of fake row elements that must compensate when scrollerEl has scrollbars

                // when the time-grid isn't tall enough to occupy the given height, we render an <hr> underneath
                bottomRuleEl: null,
                bottomRuleHeight: null,

                initialize: function () {
                    this.timeGrid = new TimeGrid(this);

                    if (this.opt('allDaySlot')) { // should we display the "all-day" area?
                        this.dayGrid = new DayGrid(this); // the all-day subcomponent of this view

                        // the coordinate grid will be a combination of both subcomponents' grids
                        this.coordMap = new ComboCoordMap([
                            this.dayGrid.coordMap,
                            this.timeGrid.coordMap
                        ]);
                    } else {
                        this.coordMap = this.timeGrid.coordMap;
                    }
                },

                /* Rendering
                 ------------------------------------------------------------------------------------------------------------------*/


                // Sets the display range and computes all necessary dates
                setRange: function (range) {
                    View.prototype.setRange.call(this, range); // call the super-method

                    this.timeGrid.setRange(range);
                    if (this.dayGrid) {
                        this.dayGrid.setRange(range);
                    }
                },

                // Renders the view into `this.el`, which has already been assigned
                render: function () {

                    this.el.addClass('fc-agenda-view').html(this.renderHtml());

                    // the element that wraps the time-grid that will probably scroll
                    this.scrollerEl = this.el.find('.fc-time-grid-container');
                    this.timeGrid.coordMap.containerEl = this.scrollerEl; // don't accept clicks/etc outside of this

                    this.timeGrid.el = this.el.find('.fc-time-grid');
                    this.timeGrid.render();

                    // the <hr> that sometimes displays under the time-grid
                    this.bottomRuleEl = $('<hr class="' + this.widgetHeaderClass + '"/>')
                            .appendTo(this.timeGrid.el); // inject it into the time-grid

                    if (this.dayGrid) {
                        this.dayGrid.el = this.el.find('.fc-day-grid');
                        this.dayGrid.render();

                        // have the day-grid extend it's coordinate area over the <hr> dividing the two grids
                        this.dayGrid.bottomCoordPadding = this.dayGrid.el.next('hr').outerHeight();
                    }

                    this.noScrollRowEls = this.el.find('.fc-row:not(.fc-scroller *)'); // fake rows not within the scroller
                },

                // Make subcomponents ready for cleanup
                destroy: function () {
                    this.timeGrid.destroy();
                    if (this.dayGrid) {
                        this.dayGrid.destroy();
                    }
                    View.prototype.destroy.call(this); // call the super-method
                },

                // Builds the HTML skeleton for the view.
                // The day-grid and time-grid components will render inside containers defined by this HTML.
                renderHtml: function () {
                    return '' +
                            '<table>' +
                            '<thead>' +
                            '<tr>' +
                            '<td class="' + this.widgetHeaderClass + '">' +
                            this.timeGrid.headHtml() + // render the day-of-week headers
                            '</td>' +
                            '</tr>' +
                            '</thead>' +
                            '<tbody>' +
                            '<tr>' +
                            '<td class="' + this.widgetContentClass + '">' +
                            (this.dayGrid ?
                                    '<div class="fc-day-grid"/>' +
                                    '<hr class="' + this.widgetHeaderClass + '"/>' :
                                    ''
                                    ) +
                            '<div class="fc-time-grid-container">' +
                            '<div class="fc-time-grid"/>' +
                            '</div>' +
                            '</td>' +
                            '</tr>' +
                            '</tbody>' +
                            '</table>';
                },

                // Generates the HTML that will go before the day-of week header cells.
                // Queried by the TimeGrid subcomponent when generating rows. Ordering depends on isRTL.
                headIntroHtml: function () {
                    var date;
                    var weekNumber;
                    var weekTitle;
                    var weekText;

                    if (this.opt('weekNumbers')) {
                        date = this.timeGrid.getCell(0).start;
                        weekNumber = this.calendar.calculateWeekNumber(date);
                        weekTitle = this.opt('weekNumberTitle');

                        if (this.opt('isRTL')) {
                            weekText = weekNumber + weekTitle;
                        } else {
                            weekText = weekTitle + weekNumber;
                        }

                        return '' +
                                '<th class="fc-axis fc-week-number ' + this.widgetHeaderClass + '" ' + this.axisStyleAttr() + '>' +
                                '<span>' + // needed for matchCellWidths
                                htmlEscape(weekText) +
                                '</span>' +
                                '</th>';
                    } else {
                        return '<th class="fc-axis ' + this.widgetHeaderClass + '" ' + this.axisStyleAttr() + '></th>';
                    }
                },

                // Generates the HTML that goes before the all-day cells.
                // Queried by the DayGrid subcomponent when generating rows. Ordering depends on isRTL.
                dayIntroHtml: function () {
                    return '' +
                            '<td class="fc-axis ' + this.widgetContentClass + '" ' + this.axisStyleAttr() + '>' +
                            '<span>' + // needed for matchCellWidths
                            (this.opt('allDayHtml') || htmlEscape(this.opt('allDayText'))) +
                            '</span>' +
                            '</td>';
                },

                // Generates the HTML that goes before the bg of the TimeGrid slot area. Long vertical column.
                slotBgIntroHtml: function () {
                    return '<td class="fc-axis ' + this.widgetContentClass + '" ' + this.axisStyleAttr() + '></td>';
                },

                // Generates the HTML that goes before all other types of cells.
                // Affects content-skeleton, helper-skeleton, highlight-skeleton for both the time-grid and day-grid.
                // Queried by the TimeGrid and DayGrid subcomponents when generating rows. Ordering depends on isRTL.
                introHtml: function () {
                    return '<td class="fc-axis" ' + this.axisStyleAttr() + '></td>';
                },

                // Generates an HTML attribute string for setting the width of the axis, if it is known
                axisStyleAttr: function () {
                    if (this.axisWidth !== null) {
                        return 'style="width:' + this.axisWidth + 'px"';
                    }
                    return '';
                },

                /* Dimensions
                 ------------------------------------------------------------------------------------------------------------------*/


                updateSize: function (isResize) {
                    if (isResize) {
                        this.timeGrid.resize();
                    }
                    View.prototype.updateSize.call(this, isResize);
                },

                // Refreshes the horizontal dimensions of the view
                updateWidth: function () {
                    // make all axis cells line up, and record the width so newly created axis cells will have it
                    this.axisWidth = matchCellWidths(this.el.find('.fc-axis'));
                },

                // Adjusts the vertical dimensions of the view to the specified values
                setHeight: function (totalHeight, isAuto) {
                    var eventLimit;
                    var scrollerHeight;

                    if (this.bottomRuleHeight === null) {
                        // calculate the height of the rule the very first time
                        this.bottomRuleHeight = this.bottomRuleEl.outerHeight();
                    }
                    this.bottomRuleEl.hide(); // .show() will be called later if this <hr> is necessary

                    // reset all dimensions back to the original state
                    this.scrollerEl.css('overflow', '');
                    unsetScroller(this.scrollerEl);
                    uncompensateScroll(this.noScrollRowEls);

                    // limit number of events in the all-day area
                    if (this.dayGrid) {
                        this.dayGrid.destroySegPopover(); // kill the "more" popover if displayed

                        eventLimit = this.opt('eventLimit');
                        if (eventLimit && typeof eventLimit !== 'number') {
                            eventLimit = AGENDA_ALL_DAY_EVENT_LIMIT; // make sure "auto" goes to a real number
                        }
                        if (eventLimit) {
                            this.dayGrid.limitRows(eventLimit);
                        }
                    }

                    if (!isAuto) { // should we force dimensions of the scroll container, or let the contents be natural height?

                        scrollerHeight = this.computeScrollerHeight(totalHeight);
                        if (setPotentialScroller(this.scrollerEl, scrollerHeight)) { // using scrollbars?

                            // make the all-day and header rows lines up
                            compensateScroll(this.noScrollRowEls, getScrollbarWidths(this.scrollerEl));

                            // the scrollbar compensation might have changed text flow, which might affect height, so recalculate
                            // and reapply the desired height to the scroller.
                            scrollerHeight = this.computeScrollerHeight(totalHeight);
                            this.scrollerEl.height(scrollerHeight);

                            this.restoreScroll();
                        } else { // no scrollbars
                            // still, force a height and display the bottom rule (marks the end of day)
                            this.scrollerEl.height(scrollerHeight).css('overflow', 'hidden'); // in case <hr> goes outside
                            this.bottomRuleEl.show();
                        }
                    }
                },

                // Sets the scroll value of the scroller to the initial pre-configured state prior to allowing the user to change it
                initializeScroll: function () {
                    var _this = this;
                    var scrollTime = moment.duration(this.opt('scrollTime'));
                    var top = this.timeGrid.computeTimeTop(scrollTime);

                    // zoom can give weird floating-point values. rather scroll a little bit further
                    top = Math.ceil(top);

                    if (top) {
                        top++; // to overcome top border that slots beyond the first have. looks better
                    }

                    function scroll() {
                        _this.scrollerEl.scrollTop(top);
                    }

                    scroll();
                    setTimeout(scroll, 0); // overrides any previous scroll state made by the browser
                },

                /* Events
                 ------------------------------------------------------------------------------------------------------------------*/


                // Renders events onto the view and populates the View's segment array
                renderEvents: function (events) {
                    var dayEvents = [];
                    var timedEvents = [];
                    var daySegs = [];
                    var timedSegs;
                    var i;

                    // separate the events into all-day and timed
                    for (i = 0; i < events.length; i++) {
                        if (events[i].allDay) {
                            dayEvents.push(events[i]);
                        } else {
                            timedEvents.push(events[i]);
                        }
                    }

                    // render the events in the subcomponents
                    timedSegs = this.timeGrid.renderEvents(timedEvents);
                    if (this.dayGrid) {
                        daySegs = this.dayGrid.renderEvents(dayEvents);
                    }

                    // the all-day area is flexible and might have a lot of events, so shift the height
                    this.updateHeight();
                },

                // Retrieves all segment objects that are rendered in the view
                getEventSegs: function () {
                    return this.timeGrid.getEventSegs().concat(
                            this.dayGrid ? this.dayGrid.getEventSegs() : []
                            );
                },

                // Unrenders all event elements and clears internal segment data
                destroyEvents: function () {

                    // if destroyEvents is being called as part of an event rerender, renderEvents will be called shortly
                    // after, so remember what the scroll value was so we can restore it.
                    this.recordScroll();

                    // destroy the events in the subcomponents
                    this.timeGrid.destroyEvents();
                    if (this.dayGrid) {
                        this.dayGrid.destroyEvents();
                    }

                    // we DON'T need to call updateHeight() because:
                    // A) a renderEvents() call always happens after this, which will eventually call updateHeight()
                    // B) in IE8, this causes a flash whenever events are rerendered
                },

                /* Dragging (for events and external elements)
                 ------------------------------------------------------------------------------------------------------------------*/


                // A returned value of `true` signals that a mock "helper" event has been rendered.
                renderDrag: function (dropLocation, seg) {
                    if (dropLocation.start.hasTime()) {
                        return this.timeGrid.renderDrag(dropLocation, seg);
                    } else if (this.dayGrid) {
                        return this.dayGrid.renderDrag(dropLocation, seg);
                    }
                },

                destroyDrag: function () {
                    this.timeGrid.destroyDrag();
                    if (this.dayGrid) {
                        this.dayGrid.destroyDrag();
                    }
                },

                /* Selection
                 ------------------------------------------------------------------------------------------------------------------*/


                // Renders a visual indication of a selection
                renderSelection: function (range) {
                    if (range.start.hasTime() || range.end.hasTime()) {
                        this.timeGrid.renderSelection(range);
                    } else if (this.dayGrid) {
                        this.dayGrid.renderSelection(range);
                    }
                },

                // Unrenders a visual indications of a selection
                destroySelection: function () {
                    this.timeGrid.destroySelection();
                    if (this.dayGrid) {
                        this.dayGrid.destroySelection();
                    }
                }

            });

            /* A week view with an all-day cell area at the top, and a time grid below
             ----------------------------------------------------------------------------------------------------------------------*/

            fcViews.agendaWeek = {
                type: 'agenda',
                duration: {weeks: 1}
            };
            /* A day view with an all-day cell area at the top, and a time grid below
             ----------------------------------------------------------------------------------------------------------------------*/

            fcViews.agendaDay = {
                type: 'agenda',
                duration: {days: 1}
            };
        });